ACOG/SMFM Consensus www.AJOG.org

ACOG/SMFM OBSTETRIC CARE CONSENSUS Safe prevention of the primary cesarean delivery This document was developed jointly by the American College of Obstetricians and Gynecologists (the College) and the Society for MaternaleFetal Medicine with the assistance of Aaron B. Caughey, MD, PhD; Alison G. Cahill, MD, MSCI; Jeanne-Marie Guise, MD, MPH; and Dwight J. Rouse, MD, MSPH

The information reflects emerging clinical and scientific advances as of the date issued, is subject to change, and should not be construed as dictating an exclusive course of treatment or procedure. Variations in practice may be warranted based on the needs of the individual patient, resources, and limitations unique to the institution or type of practice.

Background In 2011, 1 in 3 women who gave birth In 2011, 1 in 3 women who gave birth in the United States did so by cesarean delivery. in the United States did so by cesarean Cesarean birth can be lifesaving for the fetus, the mother, or both in certain cases. delivery.1 Even though the rates of pri- However, the rapid increase in cesarean birth rates from 1996 through 2011 without mary and total cesarean delivery have clear evidence of concomitant decreases in maternal or neonatal morbidity or mortality plateaued recently, there was a rapid raises significant concern that cesarean delivery is overused. Variation in the rates of increase in cesarean rates from 1996 nulliparous, term, singleton, vertex cesarean births also indicates that clinical practice through 2011 (Figure 1). Although ce- patterns affect the number of cesarean births performed. The most common indications sarean delivery can be lifesaving for the for primary cesarean delivery include, in order of frequency, labor dystocia, abnormal or fetus, the mother, or both in certain indeterminate (formerly, nonreassuring) fetal heart rate tracing, fetal malpresentation, cases, the rapid increase in the rate multiple gestation, and suspected fetal macrosomia. Safe reduction of the rate of pri- of cesarean births without evidence of mary cesarean deliveries will require different approaches for each of these, as well as concomitant decreases in maternal or other, indications. For example, it may be necessary to revisit the definition of labor neonatal morbidity or mortality raises dystocia because recent data show that contemporary labor progresses at a rate significant concern that cesarean de- substantially slower than what was historically taught. Additionally, improved and livery is overused.2 Therefore, it is standardized fetal heart rate interpretation and management may have an effect. important for health care providers to Increasing women’s access to nonmedical interventions during labor, such as con- understand the short-term and long- tinuous labor and delivery support, also has been shown to reduce cesarean birth rates. term tradeoffs between cesarean and External cephalic version for breech presentation and a trial of labor for women with twin vaginal delivery, as well as the safe and gestations when the first twin is in cephalic presentation are other of several examples appropriate opportunities to prevent of interventions that can contribute to the safe lowering of the primary cesarean overuse of cesarean delivery, particularly delivery rate. primary cesarean delivery.

Balancing risks and benefits Childbirth by its very nature carries po- conditionsesuch as placenta previa or delivery, although there was crossover in tential risks for the woman and her baby, uterine ruptureecesarean delivery is both treatment arms.5 In this study, at regardless of the route of delivery. firmly established as the safest route of 3-month follow-up, women were more The National Institutes of Health has delivery. However, for most pregnancies, likely to have urinary, but not fecal, in- commissioned evidence-based reports which are low-risk, cesarean delivery continence if they had been randomized over recent years to examine the risks appears to pose greater risk of maternal to the planned vaginal delivery group. and benefits of cesarean and vaginal morbidity and mortality than vaginal However, this difference was no longer 3 delivery (Table 1). For certain clinical delivery4 (Table 1). significant at 2-year follow-up.6 Because It is difficult to isolate the morbidity of the size of this randomized trial, it was fi The authors report no conflict of interest. caused speci cally by route of delivery. not powered to look at other measures of This article is being published concurrently in the For example, in one of the few ran- maternal morbidity. March 2014 issue of Obstetrics & Gynecology domized trials of approach to delivery, A large population-based study from (Obstet Gynecol 2014;123:693-711). women with a breech presentation Canada found that the risk of severe http://dx.doi.org/10.1016/j.ajog.2014.01.026 were randomized to undergo planned maternal morbiditiesedefined as hem- cesarean delivery or planned vaginal orrhage that requires hysterectomy or

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substantial hospital-level variation. FIGURE 1 Studies have shown a 10-fold variation US delivery rates, 1989 through 2011 in the cesarean delivery rate across hos- pitals in the United States, from 7.1- 69.9%, and a 15-fold variation among low-risk women, from 2.4-36.5%.12 Studies that have evaluated the role of maternal characteristics, such as age, weight, and ethnicity, have con- sistently found these factors do not account fully for the temporal increase in the cesarean delivery rate or its regional variations.13-15 These findings suggest that other potentially modifiable factors, such as patient preferences and practice variation among hospitals, sys- tems, and health care providers, likely contribute to the escalating cesarean delivery rates. To understand the degree to which cesarean deliveries may be preventable, it is important to know why cesareans are performed. In a 2011 population-based study, the most common indications for primary cesarean delivery included, in CD, cesarean delivery; VBAC, vaginal birth after cesarean delivery. order of frequency, labor dystocia, *Percent of women who have VBAC; yRate based on total number of deliveries. abnormal or indeterminate (formerly, Data from National Vital Statistics and from Martin et al.77 nonreassuring) fetal heart rate tracing, ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. fetal malpresentation, multiple ges- tation, and suspected fetal macrosomia (Figure 3).16 Arrest of labor and abnor- mal or indeterminate fetal heart rate tracing accounted for more than half of transfusion, uterine rupture, anesthetic nearly 40%.8 This combination of com- all primary cesarean deliveries in the complications, shock, cardiac arrest, plications not only significantly increases study population. Safe reduction of the acute renal failure, assisted ventilation, maternal morbidity but also increases rate of primary cesarean deliveries will venous thromboembolism, major infec- the risk of adverse neonatal outcomes, require different approaches for each tion, or in-hospital wound disruption such as neonatal intensive care unit of these indications. For example, it may or hematomaewas increased 3-fold admission and perinatal death.3,9,10 be necessary to revisit the definition of for cesarean delivery as compared with Thus, although the initial cesarean de- labor dystocia because recent data show vaginal delivery (2.7% vs 0.9%, respec- livery is associated with some increases that contemporary labor progresses at tively).7 There also are concerns regard- in morbidity and mortality, the down- a rate substantially slower than what has ing the long-term risks associated with stream effects are even greater because of been historically taught. Improved and cesarean delivery, particularly those the risks from repeat cesareans in future standardized fetal heart rate inter- associated with subsequent pregnancies. pregnancies.11 pretation and management also may The incidence of placental abnormal- have an effect. Increasing women’s access ities, such as placenta previa, in future Indications for primary cesarean to nonmedical interventions during la- pregnancies increases with each subse- There is great regional variation by state bor, such as continuous labor support, quent cesarean delivery, from 1% with in the rate of total cesarean delivery also has been shown to reduce cesarean 1 prior cesarean delivery to almost 3% across the United States, ranging from birth rates. External cephalic version with 3 prior cesarean deliveries. In a low of 23% to a high of nearly 40% for breech presentation and a trial of addition, an increasing number of prior (Figure 2). Variation in the rates of labor for women with twin gestations cesareans is associated with the mor- nulliparous term singleton vertex when the first twin is in cephalic bidity of placental previa: after 3 cesarean cesarean births indicates that clinical presentation also can contribute to the deliveries, the risk that a placenta previa practice patterns affect the number of safe lowering of the primary cesarean will be complicated by placenta accreta is cesarean births performed. There also is delivery rate.

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CLINICAL MANAGEMENT Q&A TABLE 1 Risk of adverse maternal and neonatal outcomes by mode of delivery What is the appropriate definition of Risk abnormally progressing first-stage Outcome Vaginal delivery Cesarean delivery labor? Maternal Definition of abnormal Overall severe morbidity 8.6% 9.2%a a first-stage labor and mortality 0.9% 2.7% The first stage of labor has been histor- Maternal mortalityb 3.6:100,000 13.3:100,000 ically divided into the latent phase and Amniotic fluid embolismc 3.3-7.7:100,000 15.8:100,000 the active phase based on the work by Third- or fourth-degree 1.0-3.0% NA (scheduled delivery) Friedman in the 1950s and beyond. 117 fi perineal laceration The latent phase of labor is de ned as d beginning with maternal perception of Placental abnormalities Increased with prior cesarean vs vaginal delivery, and 17 risk continues to increase with each subsequent regular contractions. On the basis of cesarean delivery the 95th percentile threshold, histori- 6 cally, the latent phase has been defined as Urinary incontinence No difference between cesarean and vaginal delivery at 2 y prolonged when it is >20 hours in nul- Postpartum depression117 No difference between cesarean and vaginal delivery > liparous women and 14 hours in Neonatal multiparous women.18 The active phase Laceration2 NA 1.0-2.0% of labor has been defined as the point at 2 which the rate of change of cervical Respiratory morbidity <1.0% 1.0-4.0% (without labor) dilation significantly increases. Shoulder dystocia 1.0-2.0% 0%

Active-phase labor abnormalities can NA, not available. be categorized either as protraction dis- a Defined as 1 of following: death, postpartum bleeding, genital tract injury; wound disruption, wound infection, or both; orders (slower progress than normal) or systemic infection; b Defined as any 1 of following: death, hemorrhage requiring hysterectomy or transfusion; uterine rupture; anesthetic complications; shock; cardiac arrest; acute renal failure; assisted ventilation venous thromboembolic event; major arrest disorders (complete cessation of infection; in-hospital wound disruption, wound hematoma, or both. Data from Liu et al7; c Data from Deneux-Tharaux C progress). Based on Friedman’s work, the et al115; d Data from Abenhaim et al116; e Data from Silver et al.8 traditional definition of a protracted ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. active phase (based on the 95th percen- tile) has been cervical dilatation in the < active phase of 1.2 cm/h for nulliparous FIGURE 2 < women and 1.5 cm/h for multiparous US total cesarean delivery rates by state, 2010 women.19 Active-phase arrest tradition- ally has been defined as the absence of cervical change for 2 hours in the presence of adequate uterine contractions and cervical dilation of at least 4 cm. However, more recent data from the Consortium on Safe Labor have been used to revise the definition of con- temporary normal labor progress.20 In this retrospective study conducted at 19 US hospitals, the duration of labor was analyzed in 62,415 parturient women, each of whom delivered a singleton ver- tex fetus vaginally and had a normal perinatal outcome. In this study, the 95th percentile rate of active-phase dilation was substantially slower than the standard rate derived from Fried- man’s work, varying from 0.5e0.7 cm/h for nulliparous women and from Data from Martin et al.77 0.5e1.3 cm/h for multiparous women ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. (the ranges reflect that at more advanced

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Second, the maximal slope in the rate FIGURE 3 of change of cervical dilation over time Indications for primary cesarean delivery (ie, the active phase) often did not start until at least 6 cm. The Consortium on Safe Labor data do not directly address an optimal duration for the diagnosis of active-phase protraction or labor arrest, but do suggest that neither should be diagnosed <6 cm of dilation. Because they are contemporary and robust, it seems that the Consortium on Safe Labor data, rather than the standards proposed by Friedman, should inform evidence- based labor management.

How should abnormally progressing first-stage labor be managed?

Management of abnormal first-stage labor Although labor management strategies predicated on the recent Consortium on Safe Labor information have not been assessed yet, some insight into how management of abnormal first-stage la- bor might be optimized can be deduced from prior studies. The definitions of a prolonged latent phase are still based on data from Fried- Data from Barber et al.16 ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. man and modern investigators have not particularly focused on the latent phase of labor. Most women with a prolonged dilation, labor proceeded more quickly) First, from 4-6 cm, nulliparous and latent phase ultimately will enter the (Table 2). multiparous women dilated at essentially active phase with expectant management. The Consortium on Safe Labor data the same rate, and more slowly than his- With few exceptions, the remainder either highlight 2 important features of con- torically described. Beyond 6 cm, multi- will cease contracting or, with amniotomy temporary labor progress (Figure 4). parous women dilated more rapidly. or oxytocin (or both), achieve the active phase.18 Thus, a prolonged latent phase (eg, >20 hours in nulliparous women and TABLE 2 >14 hours in multiparous women) Spontaneous labor progress stratified by cervical dilation and parity should not be an indication for cesarean Median elapsed time, h delivery (Table 3 and Appendix). fi Parity 0 Parity 1 Parity ‡2 When the rst stage of labor is pro- Cervical dilation, cm (95th percentile) (95th percentile) (95th percentile) tracted or arrested, oxytocin is commonly 3-4 1.8 (8.1) ee recommended. Several studies have eval- uated the optimal duration of oxytocin 4-5 1.3 (6.4) 1.4 (7.3) 1.4 (7.0) augmentation in the face of labor pro- 5-6 0.8 (3.2) 0.8 (3.4) 0.8 (3.4) traction or arrest. A prospective study of 6-7 0.6 (2.2) 0.5 (1.9) 0.5 (1.8) the progress of labor in 220 nulliparous women and 99 multiparous women who 7-8 0.5 (1.6) 0.4 (1.3) 0.4 (1.2) spontaneously entered labor evaluated the 8-9 0.5 (1.4) 0.3 (1.0) 0.3 (0.9) benefit of prolonging oxytocin augmen- 9-10 0.5 (1.8) 0.3 (0.9) 0.3 (0.8) tation for an additional 4 hours (for a total Modified from Zhang et al.20 of 8 hours) in patients who were dilated at ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. least 3 cm and had unsatisfactory progress (either protraction or arrest) after an

182 American Journal of Obstetrics & Gynecology MARCH 2014 www.AJOG.org ACOG/SMFM Consensus initial 4-hour augmentation period.21 The researchers found that of women TABLE 3 who received at least 4 additional hours of Recommendations for safe prevention of primary cesarean delivery oxytocin, 38% delivered vaginally, and Recommendations Grade of recommendations none had neonates with 5-minute Apgar First stage of labor scores of <6. In nulliparous women, a period of 8 hours of augmentation A prolonged latent phase (eg, >20 h in nulliparous 1B women and >14 h in multiparous women) should not be Strong recommendation, resulted in an 18% cesarean delivery rate indication for cesarean delivery. moderate-quality evidence and no cases of birth injury or asphyxia, whereas if the period of augmentation Slow but progressive labor in first stage of labor should 1B not be indication for cesarean delivery. Strong recommendation, had been limited to 4 hours, the cesarean moderate-quality evidence delivery rate would have been twice as high given the number of women who Cervical dilation of 6 cm should be considered threshold 1B fi for active phase of most women in labor. Thus, before Strong recommendation, had not made signi cant progress at 4 6 cm of dilation is achieved, standards of active-phase moderate-quality evidence hours. Thus, slow but progressive labor in progress should not be applied. fi the rst stage of labor should not be an Cesarean delivery for active-phase arrest in first stage of 1B indication for cesarean delivery (Table 3). labor should be reserved for women 6 cm of dilation Strong recommendation, A study of >500 women found that with ruptured membranes who fail to progress despite 4 h moderate-quality evidence extending the minimum period of oxy- of adequate uterine activity, or at least 6 h of oxytocin tocin augmentation for active-phase ar- administration with inadequate uterine activity and no cervical change. rest from 2 hours to at least 4 hours allowed the majority of women who had Second stage of labor not progressed at the 2-hour mark to A specific absolute maximum length of time spent 1C give birth vaginally without adversely in second stage of labor beyond which all women Strong recommendation, affecting neonatal outcome.22 The re- should undergo operative delivery has not been low-quality evidence searchers defined active-phase labor identified. arrest as 1 cm of labor progress over Before diagnosing arrest of labor in second stage, if 1B 2 hours in women who entered labor maternal and fetal conditions permit, allow for following: Strong recommendation, spontaneously and were at least 4 cm At least 2 h of pushing in multiparous women (1B) moderate-quality evidence At least 3 h of pushing in nulliparous women (1B) dilated at the time arrest was diagnosed. Longer durations may be appropriate on individualized The vaginal delivery rate for women who basis (eg, with use of epidural analgesia or with had not progressed despite 2 hours of fetal malposition) as long as progress is being oxytocin augmentation was 91% for documented. (1B) multiparous women and 74% for nulli- Operative vaginal delivery in second stage of labor by 1B parous women. For women who had not experienced and well-trained physicians should be Strong recommendation, progressed despite 4 hours of oxytocin considered safe, acceptable alternative to cesarean moderate-quality evidence delivery. Training in, and ongoing maintenance of, (and in whom oxytocin was continued at practical skills related to operative vaginal delivery should the judgment of the health care pro- be encouraged. vider), the vaginal delivery rates were Manual rotation of fetal occiput in setting of fetal 1B 88% in multiparous women and 56% in malposition in second stage of labor is reasonable Strong recommendation, nulliparous women. Subsequently, the intervention to consider before moving to operative moderate-quality evidence researchers validated these results in vaginal delivery or cesarean delivery. To safely prevent a different cohort of 501 prospectively cesarean deliveries in setting of malposition, it is treated women.23 An additional study of important to assess fetal position in second stage of labor, particularly in setting of abnormal fetal descent. 1014 women conducted by different authors demonstrated that using the Fetal heart rate monitoring same criteria in women with spontane- Amnioinfusion for repetitive variable fetal heart rate 1A ous labor or induced labor would lead decelerations may safely reduce rate of cesarean Strong recommendation, to a significantly higher proportion delivery. high-quality evidence of women achieving vaginal delivery Scalp stimulation can be used as means of assessing fetal 1C with no increase in neonatal complica- acid-base status when abnormal or indeterminate Strong recommendation, tions.24 Of note, prolonged first stage of (formerly, nonreassuring) fetal heart patterns (eg, minimal low-quality evidence labor has been associated with an variability) are present and is safe alternative to cesarean delivery in this setting. increased risk of chorioamnionitis in the studies listed, but whether this relation- ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. (continued) ship is causal is unclear (ie, evolving

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of active-phase progress should not be TABLE 3 applied (Table 3). Further, cesarean de- Recommendations for safe prevention of primary cesarean delivery livery for active-phase arrest in the first (continued) stage of labor should be reserved for Recommendations Grade of recommendations women 6 cm of dilation with ruptured membranes who fail to progress despite Induction of labor 4 hours of adequate uterine activity, or at Before 41 0/7 wks of gestation, induction of labor 1A least 6 hours of oxytocin administration generally should be performed based on maternal and Strong recommendation, with inadequate uterine activity and no fetal medical indications. Inductions at 41 0/7 wks of high-quality evidence 22 gestation should be performed to reduce risk of cesarean cervical change (Table 3). delivery and risk of perinatal morbidity and mortality. Cervical ripening methods should be used when labor is 1B What is the appropriate definition of induced in women with unfavorable cervix. Strong recommendation, abnormal second-stage labor? moderate-quality evidence If maternal and fetal status allow, cesarean deliveries for 1B The second stage of labor begins when the failed induction of labor in latent phase can be avoided by Strong recommendation, cervix becomes fully dilated and ends with allowing longer durations of latent phase (up to 24 h) and moderate-quality evidence delivery of the neonate. Parity, delayed requiring that oxytocin be administered for at least 12-18 h pushing, use of epidural analgesia, after membrane rupture before deeming induction failure. maternal body mass index, birth weight, Fetal malpresentation occiput posterior position, and fetal sta- Fetal presentation should be assessed and documented 1C tion at complete dilation all have been beginning at 36 0/7 wks of gestation to allow for external Strong recommendation, shown to affect the length of the second cephalic version to be offered. low-quality evidence stage of labor.26 Further, it is important to Suspected fetal macrosomia consider not just the mean or median duration of the second stage of labor but Cesarean delivery to avoid potential birth trauma should 2C also the 95th percentile duration. In the be limited to estimated fetal weights of at least 5000 g in Weak recommendation, women without diabetes and at least 4500 g in women low-quality evidence Consortium on Safe Labor study dis- with diabetes. Prevalence of birth weight of 5000 g is cussed earlier, although the mean and rare, and patients should be counseled that estimates of median duration of the second stage dif- fetal weight, particularly late in gestation, are imprecise. fered by 30 minutes, the 95th percentile Excessive maternal weight gain threshold was approximately 1 hour lon- ger in women who received epidural Women should be counseled about IOM maternal weight 1B 20 guidelines in attempt to avoid excessive weight gain. Strong recommendation, analgesia than in those who did not. moderate-quality evidence Defining what constitutes an appro- Twin gestations priate duration of the second stage is not straightforward because it involves Perinatal outcomes for twin gestations in which first twin 1B a consideration of multiple short-term is in cephalic presentation are not improved by cesarean Strong recommendation, delivery. Thus, women with either cephalic/cephalic- moderate-quality evidence and long-term maternal and neonatal presenting twins or cephalic/noncephalic presenting outcomesesome of them competing. twins should be counseled to attempt vaginal delivery. Multiple investigators have examined the Other relationship between the duration of the second stage of labor and adverse Individuals, organizations, and governing bodies should 1C maternal and neonatal outcomes in an work to ensure that research is conducted to provide Strong recommendation, fi better knowledge base to guide decisions regarding low-quality evidence attempt to de ne what should constitute cesarean delivery and to encourage policy changes that a “normal” duration of the second stage. safely lower rate of primary cesarean delivery. In the era of electronic fetal monitoring,

IOM, Institute of Medicine. among neonates born to nulliparous ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. women, adverse neonatal outcomes generally have not been associated with the duration of the second stage of labor. chorioamnionitis may predispose to Given these data, as long as fetal and In a secondary analysis of a multicenter longer labors). Thus, although this rela- maternal status are reassuring, cervical randomized study of fetal pulse oxime- tionship needs further elucidation, nei- dilation of 6 cm should be considered the try, of 4126 nulliparous women who ther chorioamnionitis nor its duration threshold for the active phase of most reached the second stage of labor, none should be an indication for cesarean women in labor (Box). Thus, before of the following neonatal outcomes was delivery.25 6 cm of dilation is achieved, standards found to be related to the duration of the

184 American Journal of Obstetrics & Gynecology MARCH 2014 www.AJOG.org ACOG/SMFM Consensus second stage, which in some cases was 5 and the associated risks of perineal DEFINITION OF ARREST OF LABOR IN hours: 5-minute Apgar score of <4, um- trauma).32 With appropriate monitor- FIRST STAGE bilical artery pH <7.0, intubation in the ing, however, the absolute risks of Spontaneous labor: 6 cm dilation with delivery room, need for admission to the adverse fetal and neonatal consequences membrane rupture and 1 of following: neonatal intensive care unit, or neonatal of increasing second-stage duration 4 h of adequate contractions (eg, >200 sepsis.27 Similarly, in a secondary analysis appear to be, at worst, low and incre- Montevideo units); 6 h of inadequate of 1862 women enrolled in an early vs mental. For example, in the study of contractions and no cervical change. delayed pushing trial, a longer duration 58,113 multiparous women cited earlier, of active pushing was not associated although the risk of a 5-minute Apgar with adverse neonatal outcomes, even in score of <7 and birth depression was duration should be an indication for 28 women who pushed for >3hours. This increased when the second stage of labor cesarean delivery. also was found in a large, retrospective lasted >2 hours, the absolute risk of these cohort study of 15,759 nulliparous outcomes was low (<1.5%) with dura- How should abnormally progressing women even in a group of women whose tions <2 hours and was not doubled even second-stage labor be managed? second stage progressed >4hours.29 with durations >5 hours. Moreover, the The duration of the second stage of duration of the second stage of labor was Given the available literature, before labor and its relationship to neonatal unrelated to the risk of neonatal sepsis or diagnosing arrest of labor in the second outcomes has been less extensively major trauma. Thus, a specific absolute stage and if the maternal and fetal con- studied in multiparous women. In 1 maximum length of time spent in the ditions permit, at least 2 hours of push- retrospective study of 5158 multiparous second stage of labor beyond which all ing in multiparous women and at least women, when the duration of the second women should undergo operative de- 3 hours of pushing in nulliparous stage of labor was >3 hours, the risk of livery has not been identified (Table 3). women should be allowed (Table 3). a 5-minute Apgar score of <7, admission Similar to the first stage of labor, a pro- Longer durations may be appropriate on to the neonatal intensive care unit, and longed second stage of labor has been an individualized basis (eg, with the a composite of neonatal morbidity were associated with an increased risk of use of epidural analgesia or with fetal all significantly increased.30 A popula- chorioamnionitis in the studies listed, malposition) as long as progress is being tion-based study of 58,113 multiparous but whether this relationship is causal documented (Table 3). For example, women yielded similar results when the is unclear (ie, evolving chorioamnio- the recent Eunice Kennedy Shriver duration of the second stage was >2 nitis may predispose to longer labors). National Institute of Child Health hours.31 Again, neither chorioamnionitis nor its and Human Development document A longer duration of the second stage of labor is associated with adverse maternal outcomes, such as higher rates FIGURE 4 of puerperal infection, third-degree and Average labor curves by parity in singleton term pregnancies fourth-degree perineal lacerations, and with spontaneous onset of labor, vaginal delivery, and postpartum hemorrhage.27 Moreover, normal neonatal outcomes for each hour of the second stage, the chance for spontaneous vaginal delivery decreases progressively. Researchers have found that after a 3-hour second stage of labor, only 1 in 4 nulliparous women27 and 1 in 3 multiparous women give birth spontaneously, whereas up to 30-50% may require operative delivery to give birth vaginally in the current second stage of labor threshold environment.30 Thus, the literature supports that for women, longer time in the second stage of labor is associated with increased risks of morbidity and a decreasing probabil- ity of spontaneous vaginal delivery. However, this risk increase may not be entirely related to the duration of the P0, nulliparous women; P1, women of parity 1; P2+, women of parity 2. second stage per se, but rather to health Modified from Zhang et al.20 care provider actions and interventions ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014. in response to it (eg, operative delivery

MARCH 2014 American Journal of Obstetrics & Gynecology 185 ACOG/SMFM Consensus www.AJOG.org suggested allowing 1 additional hour in reasonable in selected cases,38 these reduction in cesarean delivery (9% vs the setting of an epidural, thus, at least procedures require a higher level of skill 41%, P <.001) associated with the use of 3 hours in multiparous women and and are more likely to fail than low manual rotation.43 Of the 731 women in 4 hours in nulliparous women be used to (+2) or outlet (scalp visible at the this study who underwent manual rota- diagnose second-stage arrest, although introitus) operative deliveries. Per- tion, none experienced an umbilical cord that document did not clarify between forming low or outlet procedures in prolapse. Further, there was no difference pushing time or total second stage.33 fetuses not believed to be macrosomic in either birth trauma or neonatal acid- is likely to safely reduce the risk of ce- emia between neonates who had experi- What other management approaches sarean delivery in the second stage of enced an attempt at manual rotation vs may reduce cesarean deliveries in the labor. However, the number of health those who had not.43 To consider an second stage of labor? care providers who are adequately intervention for a fetal malposition, the trained to perform forceps and vacuum proper assessment of fetal position must In addition to greater expectant manage- deliveries is decreasing. In one survey, be made. Intrapartum ultrasonography ment of the second stage, 2 other prac- most (55%) resident physicians in has been used to increase the accurate tices could potentially reduce cesarean training did not feel competent to per- diagnosis of fetal position when the dig- deliveries in the second stage: (1) operative form a forceps delivery upon com- ital examination results are uncertain.47 vaginal delivery; and (2) manual rotation pletion of residency.39 Thus, training Given these data, which are limited of the fetal occiput for malposition. resident physicians in the performance for safety and efficacy, manual rotation of operative vaginal deliveries and using of the fetal occiput in the setting of Operative vaginal delivery simulation for retraining and ongoing fetal malposition in the second stage of In contrast with the increasing rate of maintenance of practice would likely labor is a reasonable intervention to cesarean delivery, the rates of operative contribute to a safe lowering of the ce- consider before moving to operative vaginal deliveries (via either vacuum sarean delivery rate.40 In sum, operative vaginal delivery or cesarean delivery. or forceps) have decreased significantly vaginal delivery in the second stage of To safely prevent cesarean deliveries during the past 15 years.34 Yet, compar- labor by experienced and well-trained in the setting of malposition, it is ison of the outcomes of operative vaginal physicians should be considered a safe, important to assess the fetal position in deliveries and unplanned cesarean de- acceptable alternative to cesarean de- the second stage of labor, particularly liveries shows no difference in serious livery. Training in, and ongoing main- in the setting of abnormal fetal descent neonatal morbidity (eg, intracerebral tenance of, practical skills related to (Table 3). hemorrhage or death). In a large, retro- operative vaginal delivery should be spective cohort study, the rate of intra- encouraged (Table 3). Which fetal heart tracings deserve cranial hemorrhage associated with intervention, and what are these vacuum extraction did not differ sig- Manual rotation of the fetal occiput interventions? nificantly from that associated with Occiput posterior and occiput transverse either forceps delivery (odds ratio [OR], positions are associated with an increase The second most common indication 1.2; 95% confidence interval [CI], in cesarean delivery and neonatal com- for primary cesarean is an abnormal or 0.7e2.2) or cesarean delivery (OR, 0.9; plications.41,42 Historically, forceps rota- indeterminate fetal heart rate tracing 95% CI, 0.6e1.4).35 In a more recent tion of the fetal occiput from occiput (Figure 3). Given the known variation in study, forceps-assisted vaginal deliveries posterior or occiput transverse was interpretation and management of fetal were associated with a reduced risk of the common practice. Today this procedure, heart rate tracings, a standardized combined outcome of seizure, intra- although still considered a reasonable approach is a logical potential goal for ventricular hemorrhage, or subdural management approach, has fallen out of interventions to safely reduce the cesar- hemorrhage as compared with either favor and is rarely taught in the United ean delivery rate. vacuum-assisted vaginal delivery (OR, States. An alternative approach is manual Category III fetal heart rate tracings 0.60; 95% CI, 0.40e0.90) or cesarean rotation of the fetal occiput, which has are abnormal and require intervention.48 delivery (OR, 0.68; 95% CI, 0.48e0.97), been associated with a safe reduction in The elements of category III patternse with no significant difference between the risk of cesarean delivery and is sup- which include either absent fetal vacuum delivery or cesarean delivery.36 ported by the Society of Obstetricians heart rate variability with recurrent late Fewer than 3% of women in whom and Gynaecologists of Canada.43-45 For decelerations, recurrent variable de- an operative vaginal delivery has been example, in a small prospective trial of 61 celerations, or bradycardia; or a sinusoi- attempted go on to deliver by cesar- women, those who were offered a trial of dal rhythmehave been associated with ean.37 Although attempts at operative manual rotation experienced a lower rate abnormal neonatal arterial umbilical vaginal delivery from a midpelvic sta- of cesarean delivery (0%) compared with cord pH, encephalopathy, and cerebral tion (0 and +1 on the e5to+5scale)or those treated without manual rotation palsy.49-52 Intrauterine resuscitative from an occiput transverse or occiput (23%, P ¼ .001).46 A large, retrospective effortseincluding maternal reposition- posterior position with rotation are cohort study found a similar large ing and oxygen supplementation,

186 American Journal of Obstetrics & Gynecology MARCH 2014 www.AJOG.org ACOG/SMFM Consensus assessment for hypotension and tachy- is not acidotic. Spontaneous or elicited There is not consistent evidence that systole that may be corrected, and eval- heart rate accelerations are associated ST-segment analysis and fetal pulse ox- uation for other causes, such as umbilical with a normal umbilical cord arterial imetry either improve outcomes or cord prolapseeshould be performed pH (7.20).54,56 Recurrent variable de- reduce cesarean delivery rates.67,68 expeditiously; however, when such ef- celerations, thought to be a physiologic Despite the evidence that fetal scalp forts do not quickly resolve the category response to repetitive compression of sampling reduces the risk of cesarean III tracing, delivery as rapidly and as the umbilical cord, are not themselves delivery69,70 and the poor ability of safely possible is indicated. The Ameri- pathologic. However, if frequent and electronic fetal heart rate monitoring can Congress of Obstetricians and persistent, they can lead to fetal acidemia patterns to predict pH, intrapartum fetal Gynecologists (ACOG) recommends over time. Conservative measures, such scalp sampling has fallen out of favor in preparations for imminent delivery in as position change, may improve this the United States. This predominantly is the event that intrauterine resuscitative pattern. Amnioinfusion with normal due to its invasive nature, the narrow measures do not improve the fetal heart saline also has been demonstrated to clinical presentations for which it might rate pattern.48 resolve variable fetal heart rate de- be helpful, and the need for regulatory In contrast, category I fetal heart celerations57-59 and reduce the incidence measures to maintain bedside testing tracings are normal and do not require of cesarean delivery for a nonreassuring availability. Currently, this testing is not intervention other than ongoing assess- fetal heart rate pattern.59-61 Similarly, performed in most US centers and a fetal ment with continuous or intermittent other elements of category II fetal blood sampling “kit” that is approved by monitoring, given that patterns can heart rate tracings that may indicate the US Food and Drug Administration is change over time. Moderate variability fetal acidemia, such as minimal varia- not currently manufactured. and the presence of accelerations, which bility or recurrent late decelerations, The unnecessary performance of ce- are features of category I patterns, have should be approached with in utero sarean deliveries for abnormal or inde- proved to be reliable indicators of nor- resuscitation.48 terminate fetal heart rate tracings can be mal neonatal umbilical cord arterial pH Prolonged fetal heart rate de- attributed to limited knowledge about (7.20).53,54 celerations (which last >2 minutes but the ability of the patterns to predict Most intrapartum fetal heart rate <10 minutes) often require inter- neonatal outcomes and the lack of rig- tracings are category II.50,55 Category II vention. They can occur after rapid cer- orous science to guide clinical response tracings are indeterminate and com- vical change or after hypotension (ie, in to the patterns.55,71 Supplemental oxy- prise a diverse spectrum of fetal heart the setting of regional analgesia). Pro- gen,72 intravenous fluid bolus,73 and rate patterns that require evaluation, longed decelerations also may be a sign tocolytic agents74 are routine compo- continued surveillance, initiation of of complications, such as abruptio pla- nents of intrauterine resuscitation75 that appropriate corrective measures when centae, umbilical cord prolapse, or have extremely limited data for effec- indicated, and reevaluation.48 Based uterine rupture; because of their poten- tiveness or safety. Performance of these on the high rate of first cesarean tial morbidity, these complications interventions without a subsequent deliveries performed for the indication should be considered in the differential change in fetal heart rate pattern is not of “nonreassuring fetal heart rate” (also diagnosis to allow for appropriate eval- necessarily an indication for cesarean known as an “abnormal or indetermi- uation and intervention.62-64 Uterine delivery. Medication exposure, regional nate fetal heart rate”) and the rarity tachysystole, defined as >5 contractions analgesia, rapid labor progress, cervical of category III patterns, it can be in 10 minutes averaged over 30 minutes, examination, infection, maternal hypo- deduced that category II tracings likely can occur spontaneously or because of tension, and maternal fever all can affect account for most cesarean deliveries uterotonic agents (ie, oxytocin or pros- the fetal heart rate pattern.48 Attention to performed for nonreassuring fetal taglandins) and can be associated with such factors will optimize clinical deci- status.16 Thus, one important consid- fetal heart rate changes, such as pro- sion making regarding the management eration for health care providers who longed or late decelerations. Reduction of abnormal or indeterminate fetal are making the diagnosis of non- or cessation of the contractile agent or heart rate patterns and the need for reassuring fetal status with the intent to administration of a uterine relaxant, cesarean delivery. Specifically, amnioin- proceed with cesarean delivery is to such as a beta-mimetic agent, can resolve fusion for repetitive variable fetal heart ensure that clinically indicated mea- uterine tachysystole and improve the rate decelerations may safely reduce the sures have been undertaken to resolve fetal heart rate tracing.65 In contrast, rate of cesarean delivery (Table 3). Scalp the concerning elements of the cat- there are no current data to support in- stimulation can be used as a means of egory II tracing or provide reassurance terventions specifically for decelerations assessing fetal acid-base status when of fetal well-being. with “atypical features” (eg, shoulders, abnormal or indeterminate (formerly, Scalp stimulation to elicit fetal heart slow return to baseline, or variability nonreassuring) fetal heart patterns (eg, rate acceleration is an easily employed only within the deceleration) because minimal variability) are present and is tool when the cervix is dilated and can they have not been associated with fetal a safe alternative to cesarean delivery in offer clinician reassurance that the fetus acidemia.49,66 this setting (Table 3).

MARCH 2014 American Journal of Obstetrics & Gynecology 187 ACOG/SMFM Consensus www.AJOG.org

What is the effect of induction of Once a decision has been made to setting of oxytocin and ruptured mem- labor on cesarean delivery? proceed with a labor induction, varia- branes before declaring an induction tions in the management of labor in- failed.33 The use of induction of labor has duction likely affect rates of cesarean Therefore, if the maternal and fetal increased in the United States con- delivery, particularly the use of cervical status allow, cesarean deliveries for failed currently with the increase in the cesar- ripening agents for the unfavorable cer- induction of labor in the latent phase can ean delivery rate, from 9.5% of births in vix and the lack of a standard definition be avoided by allowing longer durations 1990 to 23.1% of births in 2008.76,77 of what constitutes prolonged duration of the latent phase (up to 24 hours) Because women who undergo induction of the latent phase (a failed induction). and requiring that oxytocin be admin- of labor have higher rates of cesarean Numerous studies have found that the istered for at least 12-18 hours after delivery than those who experience use of cervical ripening methodsesuch membrane rupture before deeming the spontaneous labor, it has been widely as misoprostol, dinoprostone, prosta- induction a failure (Table 3). assumed that induction of labor itself glandin E2 gel, Foley bulbs, and lami- increases the risk of cesarean delivery. naria tentselead to lower rates of What are the other indications for However, this assumption is predicated cesarean delivery than induction of labor primary cesarean delivery? What on a faulty comparison of women who without cervical ripening.69,88 The ben- alternative management strategies are induced vs women in spontaneous efit is so widely accepted that recent can be used for the safe prevention of labor.78 Studies that compare induction studies do not include a placebo or cesarean delivery in these cases? of labor to its actual alternative, expect- nonintervention group, but rather ant management awaiting spontaneous compare one cervical ripening method Although labor arrest and abnormal or labor, have found either no difference or with another.89 There also are data to indeterminate fetal heart rate tracing are a decreased risk of cesarean delivery support the use of >1 of these methods the most common indications for pri- among women who are induced.79-82 sequentially or in combination, such as mary cesarean delivery, less common This appears to be true even for women misoprostol and a Foley bulb, to facili- indicationsesuch as fetal malpresenta- with an unfavorable cervix.83 tate cervical ripening.90 Thus, cervical tion, suspected macrosomia, multiple Available randomized trial data com- ripening methods should be used when gestation, and maternal infection (eg, paring induction of labor vs expectant labor is induced in women with an un- herpes simplex virus)eaccount for tens management reinforce the more recent favorable cervix (Table 3). of thousands of cesareans deliveries in observational data. For example, a met- In the setting of induction of labor, the United States annually. Safe preven- aanalysis of prospective randomized nonintervention in the latent phase tion of primary cesarean deliveries will controlled trials conducted at <42 0/7 when the fetal heart tracing is reassuring require different approaches for each of weeks of gestation found that women and maternal and fetal statuses are stable these indications. who underwent induction of labor had seems to reduce the risk of cesarean de- a lower rate of cesarean delivery com- livery. Recent data indicate that the latent Fetal malpresentation pared with those who received expectant phase of labor is longer in induced labor Breech presentation at 37 weeks of treatment.84 In addition, a metaanalysis compared with spontaneous labor.91 gestation is estimated to complicate of 3 older, small studies of induction of Furthermore, at least 3 studies support 3.8% of pregnancies, and >85% of labor <41 0/7 weeks of gestation also that a substantial proportion of women pregnant women with a persistent breech demonstrated a statistically significant undergoing induction who remain in the presentation are delivered by cesarean.95 reduction in the rate of cesarean de- latent phase of labor for 12-18 hours In one recent study, the rate of attempted livery.85 Additionally, increases in still- with oxytocin administration and rup- external cephalic version was 46% and birth, neonatal death, and infant death tured membranes will give birth vagi- decreased during the study period.96 have been associated with gestations at nally if induction is continued.92-94 In 1 Thus, external cephalic version for fetal 41 0/7 weeks.86,87 In a 2012 Cochrane study, 17% of women were still in the malpresentation is likely underutilized, metaanalysis, induction of labor at 41 latent phase of labor at >12 hours, and especially when considering that most 0/7 weeks of gestation was associated 5% remained in the latent phase >18 patients with a successful external ce- with a reduction in perinatal mortality hours.93 In another study, of those phalic version will give birth vaginally.96 when compared with expectant man- women who were in the latent phase for Obstetricians should offer and per- agement.85 Therefore, at <41 0/7 weeks >12 hours and achieved active phase of form external cephalic version when- of gestation, induction of labor generally labor, the majority (60%) gave birth ever possible.97 Furthermore, when an should be performed based on maternal vaginally.94 Membrane rupture and external cephalic version is planned, and fetal medical indications. Inductions oxytocin administration, except in rare there is evidence that success may be at 41 0/7 weeks of gestation should be circumstances, should be considered enhanced by regional analgesia.98 Fetal performed to reduce the risk of cesarean prerequisites to any definition of failed presentation should be assessed and delivery and the risk of perinatal mor- labor induction, and experts have pro- documented beginning at 36 0/7 weeks bidity and mortality (Table 3). posed waiting at least 24 hours in the of gestation to allow for external

188 American Journal of Obstetrics & Gynecology MARCH 2014 www.AJOG.org ACOG/SMFM Consensus cephalic version to be offered (Table 3). weight-management interventions con- demonstrated that the presence of con- Before a vaginal breech delivery is tinue to be developed and have yet to tinuous one-on-one support during planned, women should be informed translate into reduced rates of cesarean labor and delivery was associated with that the risk of perinatal or neonatal delivery or morbidity, the available improved patient satisfaction and a sta- mortality or short-term serious neo- observational data support that women tistically significant reduction in the rate natal morbidity may be higher than if should be counseled about the IOM of cesarean delivery.111 Given that there a cesarean delivery is planned, and the maternal weight guidelines in an attempt are no associated measurable harms, this patient’s informed consent should be to avoid excessive weight gain (Table 3). resource is probably underutilized. documented. Twin gestation What organizational actions are Suspected fetal macrosomia The rate of cesarean deliveries among necessary for the primary cesarean Suspected fetal macrosomia is not an women with twin gestations increased delivery rate to safely decline? indication for delivery and rarely is an from 53% in 1995 to 75% in 2008.105 indication for cesarean delivery. To avoid Even among vertex-presenting twins, A number of approaches are needed to potential birth trauma, ACOG recom- 105 there was an increase from 45-68%. reduce the primary cesarean delivery mends that cesarean delivery be limited Perinatal outcomes for twin gestations in rate, which in turn would lower the to estimated fetal weights of at least fi which the rst twin is in cephalic pre- repeat cesarean delivery rate. Although 5000 g in women without diabetes and at sentation are not improved by cesarean national and regional organizations can least 4500 g in women with diabetes delivery. Thus, women with either take the lead in setting the agenda (Table 3).99 This recommendation is cephalic/cephalic-presenting twins or regarding the safe prevention of primary based on estimations of the number cephalic/noncephalic-presenting twins cesarean delivery, such an agenda will needed to treat from a study that mod- should be counseled to attempt vaginal need to be prioritized at the level of eled the potential risks and benefits from 106 delivery (Table 3). To ensure safe practices, hospitals, health care systems, a scheduled, nonmedically indicated ce- vaginal delivery of twins, it is important and, of course, patients. sarean delivery for suspected fetal mac- to train residents to perform twin de- Changing the local culture and atti- rosomia, including shoulder dystocias liveries and to maintain experience with tudes of obstetric care providers regarding and permanent brachial plexus in- twin vaginal deliveries among practicing the issues involved in cesarean delivery juries.100 The prevalence of birth weight obstetric care providers. reduction also will be challenging. Several of 5000 g is rare, and patients should studies have demonstrated the feasibility be counseled that estimates of fetal Herpes simplex virus of using systemic interventions to reduce weight, particularly late in gestation, are In women with a history of herpes sim- the rate of cesarean delivery across in- imprecise (Table 3). Even when these plex virus, the administration of acyclo- dications and across community and ac- thresholds are not reached, screening vir for viral suppression is an important ademic settings. A 2007 review found that ultrasonography performed late in strategy to prevent genital herpetic out- the cesarean delivery rate was reduced by pregnancy has been associated with the breaks requiring cesarean delivery 107,108 13% when audit and feedback were used unintended consequence of increased and asymptomatic viral shedding. exclusively but decreased by 27% when cesarean delivery with no evidence of Given the favorable benefit-risk profile audit and feedback were used as part of a neonatal benefit.101 Thus, ultrasonogra- for the administration of maternal acy- multifaceted intervention, which involved phy for estimated fetal weight in the clovir, efforts should be made to ensure second opinions and culture change.112 third trimester should be used sparingly that women with a history of genital Systemic interventions, therefore, provide and with clear indications. herpes, even in the absence of an out- break in the current pregnancy, are an important strategic opportunity for Excessive maternal weight gain offered oral suppressive therapy within reducing cesarean delivery rates. How- fi A large proportion of women in the 3-4 weeks of anticipated delivery109 and ever, the speci c interventional ap- United States gain more weight during at the latest, 36 weeks of gestation.110 proaches have not been studied in large, fi pregnancy than is recommended by the Cesarean delivery is not recommended prospective trials, thus speci crecom- Institute of Medicine (IOM). Observa- for women with a history of herpes mendations cannot be made. tional evidence suggests that women who simplex virus infection but no active A necessary component of culture gain more weight than recommended by genital disease during labor.110 change will be tort reform because the IOM guidelines have an increased risk the practice environment is extremely of cesarean delivery and other adverse Continuous labor and delivery support vulnerable to external medicolegal outcomes.15,102,103 In a recent Commit- Published data indicate that one of pressures. Studies have demonstrated tee Opinion, ACOG recommends that it the most effective tools to improve associations between cesarean delivery is “important to discuss appropriate labor and delivery outcomes is the con- rates and malpractice premiums and weight gain, diet, and exercise at the ini- tinuous presence of support personnel, state-level tort regulations, such as tial visit and periodically throughout such as a doula. A Cochrane meta- caps on damages.113,114 A broad range the pregnancy.”104 Although pregnancy analysis of 12 trials and >15,000 women of evidence-based approaches will be

MARCH 2014 American Journal of Obstetrics & Gynecology 189 ACOG/SMFM Consensus www.AJOG.org necessaryeincluding changes in indi- of Child Health and Human Development chorioamnionitis at term and its duration-rela- vidual clinician practice patterns, devel- maternal-fetal medicine units network. Obstet tionship to outcomes; National Institute of Child Gynecol 2006;107:1226-32. Health And Human Development, maternal-fetal opment of clinical management 9. Marshall NE, Fu R, Guise JM. Impact of medicine units network. Am J Obstet Gynecol guidelines from a broad range of orga- multiple cesarean deliveries on maternal mor- 2004;191:211-6. nizations, implementation of systemic bidity: a systematic review. Am J Obstet Gynecol 26. Piper JM, Bolling DR, Newton ER. The approaches at the organizational level 2011;205:262.e1-8. second stage of labor: factors influencing dura- and regional level, and tort reformeto 10. Smith GC, Pell JP, Dobbie R. Cesarean tion. Am J Obstet Gynecol 1991;165:976-9. section and risk of unexplained stillbirth in sub- 27. Rouse DJ, Weiner SJ, Bloom SL, et al. ensure that unnecessary cesarean de- sequent pregnancy. Lancet 2003;362:1779-84. Second-stage labor duration in nulliparous liveries are reduced. In addition, in- 11. Solheim KN, Esakoff TF, Little SE, women: relationship to maternal and perinatal dividuals, organizations, and governing Cheng YW, Sparks TN, Caughey AB. The effect outcomes; Eunice Kennedy Shriver National bodies should work to ensure that of cesarean delivery rates on the future incidence Institute of Child Health and Human Develop- research is conducted to provide a better of placenta previa, placenta accreta, and ment maternal-fetal medicine units network. Am maternal mortality. J Matern Fetal Neonatal Med J Obstet Gynecol 2009;201:357.e1-7. knowledge base to guide decisions 2011;24:1341-6. 28. Le Ray C, Audibert F, Goffinet F, Fraser W. regarding cesarean delivery and to 12. 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Appendix

Society for MaternaleFetal Medicine grading system: grading of recommendations assessment, development, and evaluation (GRADE) recommendations Obstetric Care Consensus documents will use Society for MaternaleFetal Medicine grading approach: http://www.ajog.org/article/S0002-9378% 2813%2900744-8/fulltext. Recommendations are classified as either strong (Grade 1) or weak (Grade 2), and quality of evidence is classified as high (Grade A), moderate (Grade B), and low (Grade C).118 Thus, recommendations can be 1 of following 6 possibilities: 1A, 1B, 1C, 2A, 2B, 2C

Grade of recommendation Clarity of risk and benefit Quality of supporting evidence Implications 1A. Strong Benefits clearly outweigh risk and Consistent evidence from well-performed Strong recommendations, recommendation, burdens, or vice versa. randomized controlled trials or overwhelming can apply to most patients in high-quality evidence evidence of some other form. Further research most circumstances without is unlikely to change confidence in estimate of reservation. Clinicians benefit and risk. should follow strong recommendation unless clear and compelling rationale for alternative approach is present. 1B. Strong Benefits clearly outweigh risk and Evidence from randomized controlled trials with Strong recommendation, and recommendation, burdens, or vice versa. important limitations (inconsistent results, applies to most patients. moderate-quality methodological flaws, indirect or imprecise), or Clinicians should follow evidence very strong evidence of some other research strong recommendation design. Further research (if performed) is likely unless clear and compelling to have impact on confidence in estimate of rationale for alternative benefit and risk and may change estimate. approach is present. 1C. Strong Benefits appear to outweigh risk Evidence from observational studies, Strong recommendation, and recommendation, and burdens, or vice versa. unsystematic clinical experience, or from applies to most patients. low-quality evidence randomized controlled trials with serious flaws. Some of evidence base Any estimate of effect is uncertain. supporting recommendation is, however, of low quality. 2A. Weak Benefits closely balanced with Consistent evidence from well-performed Weak recommendation, best recommendation, risks and burdens. randomized controlled trials or overwhelming action may differ depending high-quality evidence evidence of some other form. Further research on circumstances or patients is unlikely to change confidence in estimate of or societal values. benefit and risk. 2B. Weak Benefits closely balanced with Evidence from randomized controlled trials with Weak recommendation, recommendation, risks and burdens; some important limitations (inconsistent results, alternative approaches likely moderate-quality uncertainty in estimates of methodological flaws, indirect or imprecise), or to be better for some patients evidence benefits, risks, and burdens. very strong evidence of some other research under some circumstances. design. Further research (if performed) is likely to have effect on confidence in estimate of benefit and risk and may change estimate. 2C. Weak Uncertainty in estimates of Evidence from observational studies, Very weak recommendation, recommendation, benefits, risks, and burdens; unsystematic clinical experience, or from other alternatives may be low-quality evidence benefits may be closely balanced randomized controlled trials with serious flaws. equally reasonable. with risks and burdens. Any estimate of effect is uncertain. Best practice Recommendation in which either: (i) there is enormous amount of indirect evidence that clearly justifies strong recommendation (direct evidence would be challenging, and inefficient use of time and resources, to bring together and carefully summarize), or (ii) recommendation to contrary would be unethical. Modified from grading guide.119 ACOG. Safe prevention of primary cesarean delivery. Am J Obstet Gynecol 2014.

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