Journal of Perinatology (2011) 31, 789–793 r 2011 Nature America, Inc. All rights reserved. 0743-8346/11 www.nature.com/jp ORIGINAL ARTICLE Perinatal morbidity and mortality in late-term and post-term pregnancy. NEOSANO perinatal network’s experience in Mexico AM De los Santos-Garate1, M Villa-Guillen1, D Villanueva-Garc´ıa1, ML Vallejos-Ru´ız1 and MT Murgu´ıa-Peniche2 and the NEOSANO’s Network 1Department of Neonatology, Hospital Infantil de Mexico Federico Gomez, Me´xico City, Me´xico and 2National Center for Child and Adolescent Health (CeNSIA), Me´xico City, Me´xico Keywords: perinatal outcomes; pregnancy X40 weeks; Mexican Objective: The objective of this study is to identify adverse perinatal population outcomes associated with pregnancies at or beyond 40 weeks. Study Design: Retrospective cohort study conducted in Mexico, with information obtained from the NEOSANO’s Perinatal Network Database Post-term pregnancy is defined as gestation that extends beyond from April 2006 to April 2009. Multiple births, babies with inaccurate 42 weeks.1 The relative perinatal mortality is higher in post-term gestational age or babies with congenital malformations were excluded. delivery compared with delivery at term and has been associated Logistic regression models were used to analyze perinatal complications with an increased frequency of neonatal morbidity (meconium associated with pregnancies X40 weeks. aspiration, fetal distress, asphyxia in the neonatal period, Result: A total of 21 275 babies were analyzed; of these, 4545 (21.3%) were pneumonia, malformations, macrosomia and fetal birth injury) 6 6 of 40 to 407 weeks, 3024 (14.2%) 41 to 417 weeks and 388 (1.8%) 42 to 44 and maternal complications (cesarean section, postpartum 6 2 weeks of gestation. Adverse perinatal outcomes associated with 40 to 407 hemorrhage, labor dysfunction and obstetric trauma). Although it weeks deliveries were (odds ratio; 95% confidence interval): macrosomia is known that these risks are increased in post-term pregnancies, (1.9; 1.5 to 2.6), acute fetal distress (1.4; 1.2 to 1.7), emergency cesarean what has received less attention is whether and to what extent these delivery (1.4; 1.2 to 1.5) and chorioamnionitis (1.4; 1.2 to 1.6). Adverse risks increase before 42 weeks of gestation. Currently, the American 6 perinatal outcomes associated with 41 to 417 weeks were macrosomia (2.5; College of Obstetricians and Gynecologists (ACOG) recommends 1.8 to 3.3), chorioamnionitis (2; 1.7 to 2.3), emergency cesarean delivery initiation of antenatal surveillance between 41 and 42 weeks of (1.8; 1.6 to 2.1) and acute fetal distress (1.4; 1.1 to 1.7). Adverse perinatal gestation.3 However, some studies have demonstrated an increased outcomes associated with 42 to 44 weeks were macrosomia (7; 4.6 to 10.7), risk of perinatal complications with deliveries as early as 40 weeks. meconium aspiration syndrome (5.6; 2.8 to 11.2), neonatal death (4.8; 1.7 Caughey et al.4,5 reported that at a community hospital, maternal to 13.8), stillbirth (4.3; 1.4 to 13.5), 50 Apgar <4 (4.2; 1.1 to 15.7), and neonatal complications were observed at 40 to 42 weeks of chorioamnionitis (2.8; 2.2 to 3.9), admission to neonatal intensive care unit gestation, suggesting a need for additional study of this cohort. (2.7; 1.5 to 4.8), admission to neonatal intensive care unit or step-down unit In Mexico, there is scant information regarding the incidence (2.4; 1.5 to 3.9), acute fetal distress (1.8; 1.2 to 2.6) and emergency cesarean of and perinatal outcomes associated with pregnancies at or delivery (1.8; 1.3 to 2.4). beyond 40 weeks’ gestation. The aim of this study was to identify Conclusion: An increased risk for perinatal and maternal complications perinatal morbidity and mortality associated with late-term were detected as early as 40 weeks’ gestation. The risks of stillbirth and and post-term pregnancy, as compared with term pregnancies 6 neonatal death were significantly higher in the post-term group than the (39 to 397 weeks’ gestation). control group. Journal of Perinatology (2011) 31, 789–793; doi:10.1038/jp.2011.43; published online 16 June 2011 Methods Population Correspondence: Dr MT Murguı´a-Peniche, Area Director-Infancy, National Center for Child All babies (live birth or dead X400 g) born from April 2006 and Adolescent Health (CeNSIA), Francisco de P. Miranda 177, 1 er piso, Col. Merced Go´mez, to April 2009 at the study hospitals in NEOSANO’s Perinatal 01600 Deleg. A. Obrego´n, Me´xico, D.F., Me´xico. Network in Mexico (five hospitals at Mexico City, three hospitals E-mail: [email protected] Received 9 March 2010; revised 6 March 2011; accepted 15 March 2011; published online at Tlaxcala City and one hospital at Oaxaca City) were included. 16 June 2011 This network gathers social, gynecological, obstetric, baseline Perinatal complications in late-term and post-term pregnancies AM De los Santos-Garate et al 790 maternal medical conditions and neonatal data. Multiple births, this figure was significantly higher (40%) for those mothers who babies with congenital malformations or inaccurate gestational delivered at or beyond at 40 weeks’ gestation. The frequency of poor age were excluded. prenatal care, defined as less than four prenatal visits, was more prevalent among those pregnancies that lasted >40 weeks. The Gestational age assessment most common obstetric complications were chorioamnionitis Gestational age was calculated by dates (when known) or and prolonged rupture of membranes. Of note, 38 to 55% of the 6 7 alternatively by Ballard Score, Capurro Score or prenatal cases were delivered by emergency cesarean section. ultrasound. Table 2 summarizes the frequency of adverse perinatal outcomes by gestational age. In general, obstetric complications Design increased as gestational age advanced beyond 39 to 40 weeks. For each delivery, a trained field worker completed a questionnaire, Preeclampsia and chorioamnionitis was approximately twice as which included pertinent social, gynecological, obstetric, perinatal common in the 42 to 44-week gestational group as compared and baseline maternal medical data. All babies were followed up with the 39 weeks group. until discharge. As expected, the greater the gestational age beyond 39 weeks, We examined the following outcomes: maternal vaginal the higher the frequency of adverse neonatal outcomes, and these bleeding, chorioamnionitis, emergency cesarean delivery, elective were mainly associated with acute fetal distress, macrosomia cesarean delivery, 5 min Apgar score less than 4, acute fetal distress, and death. macrosomia, meconium aspiration syndrome, admission to The association between gestational age and adverse perinatal the neonatal intensive care or step-down unit, stillbirth and outcomes (adjusted analysis) is presented in Table 3. A significant neonatal death. increased risk of perinatal morbidity (chorioamnionitis, emergency cesarean delivery, acute fetal distress and macrosomia) was Statistical Analysis observed as early as 40 weeks compared with 39 weeks’ gestation. The population was divided into three groups: post-term (42 to 44 The same outcomes were also associated with pregnancies at weeks’ gestation), a late-term group of 40 to 406 weeks, and a 7 42 to 44 weeks, but the odds ratios were higher. Post-term second late-term group of 41 to 416 weeks’ gestation. Pregnancies 7 pregnancies also demonstrated additional complications such as at 39 to 396 weeks’ gestation were used for the control group. Risks 7 5 min Apgar score less than 4, meconium aspiration syndrome, (odds ratio; 95% confidence interval) for selected perinatal admission to the neonatal intensive care or step-down unit, outcomes were assessed by several logistic regression models stillbirth and neonatal death. controlled for cofounders: maternal age, <6 years of education, marital status, smoking during pregnancy, history of adverse perinatal outcomes (such as previous preterm birth, stillbirth Discussion and congenital malformations), maternal chronic diseases In this study, the frequency of pregnancies beyond 396 weeks (diabetes mellitus, thyroid disease), nulliparity, gestational 7 was approximately 37%. This represents an important proportion diabetes, preeclampsia, eclampsia, prenatal care and gender. of all deliveries and as such, it is important to analyze adverse SPSS 16.0 for Windows was used for analysis. perinatal outcomes in this population in order to obtain an increased understanding of the problem to be able to improve outcomes. Results Previous reports noted that the best outcomes occurred when the 6 8 There were 23 231 births in the study period; 1956 (8.4%) were length of pregnancy ranges from 37 to 417 weeks of gestation. It is excluded: 1295 (6%) multiple births, 419 (1.8%) for inaccurate widely accepted that infants born before or after this period, have gestational age and 242 (1%) for congenital malformations. The more perinatal complications. However, although controversial, gestational age was calculated by Capurro Score n ¼ 13 703 (64%), there are some studies that have found increased perinatal risk dates n ¼ 7448 (35%), prenatal ultrasound n ¼ 106 (0.5%) and as early as 40 weeks’ gestation.3,9 the New Ballard Score 18 (0.1%). A total of 21 275 infants were In this study population, the rate of adolescent women among 6 analyzed; of these, 4545 (21.3%) were 40 to 407 weeks’ gestation, pregnancies >39 weeks was higher than those of shorter duration 6 3024 (14.2%) 41 to 417 weeks’ gestation and 388 (1.8%) 42 to and the rates were also high in relation to that reported in our 44 weeks’ gestation. country, which is estimated to be 17% of all pregnancies. It would The maternal characteristics of the study population are shown be interesting to see if adolescence is related to prolonged in Table 1.