THIRD TRIMESTER ISSUES

Dr Stephen Lee Consultant Obstetrician Gynaecologist Royal Women’s Hospital THIRD TRIMESTER

• Definition – ~28 weeks gestation to birth • Routine antenatal care • Antenatal visits increasing in frequency • 28/40 - screening for GDM, Rh isoimmunisation; FBE, iron studies; syphilis, HBV, HCV, HIV in high risk populations • 36/40 – screening for GBS • Vaccinations – influenza and pertussis (dTPa) • Discussion re mode and timing of delivery • Wide range of potential issues

SMALL FOR

• Definition – estimated fetal weight <10th percentile; includes constitutionally small but well fetus and intrauterine growth restriction (IUGR) • *IUGR fetus can have EFW >10th percentile but not meeting growth potential • Incidence – 10% in developed countries, 20% in developing countries • Aetiology • Unknown 40% • Known 60% • 1/3 – genetic e.g. aneuploidy, confined placental mosaicism • 2/3 – fetal environment i.e. infection, placental dysfunction, maternal disease, multiple SGA VS IUGR

Small but not IUGR IUGR but not small *At risk of iatrogenic ?Customised growth prematurity charts SGA IUGR SIGNIFICANCE

• Antenatal stillbirths • Intrapartum stillbirths • Neonatal problems – prematurity, neonatal death, NEC, ICH, neurodevelopmental outcomes • Childhood problems – vision, neurodevelopmental outcomes • Adulthood/fetal origins of disease – CHD, T2DM, HT, premature death • Small babies contribute disproportionately to adverse perinatal outcome, mainly due to IUGR – intrauterine hypoxaemia, acidosis, prematurity and neonatal complications; BUT only 25% detected antenatally STILLBIRTHS AND NEONATAL DEATHS IN APPROPRIATE, SMALL AND LARGE FOR BIRTHWEIGHT FOR GESTATIONAL AGE INFANTS VASHEVNIK S, WALKER SP AND PERMEZEL M. ANZJOG 2007; 47: 302 - 6 .

• Retrospective analysis of 662,043 singleton, non-anomalous births recorded in the Victorian Perinatal Data Collection Unit 1992-2002 • AGA group • SB 2.88/1000 and NND 1.35/1000 • SGA group • SB 15.1/1000 and NND 3.99/1000 •  four fold increased risk of perinatal death across gestation Risk of Perinatal Mortality in each week of Gestation AGA SGA LGA 5 5.03

4

3 3.09

2.08 2 1.87 1.58 1.30 1.34 1.29 1.33 1.23 1.13 0.93 0.98 0.92 1 0.79 0.76

Perinatal Deaths per 1000 babies 1000 per Deaths Perinatal 0.70 0.63 0.59 0.70 0.44 0.40 0.33 0.32 0.23 0.21 0.17 0.26 0.16 0.12 0.14 0.13 0.16 0.16 0.19 0.19 0 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Weeks of Gestation

WHY ARE OUTCOMES BETTER?

• Appropriate timing of delivery • Term: NOW! • Preterm: latest gestation possible weighing risks of prematurity versus risks of fetal acidosis, asphyxia and fetal death • Paediatric consultation • Appropriate place of delivery • Adequate monitoring intrapartum • Timely administration of steroids HISTORY

• Past obstetric history esp. previous SGA • Medical history

• Diabetes -20% incidence of SGA

• Hypertension -15.5-40% depending on severity of HT • Renal disease • Inflammatory bowel disease - OR 2.4 for LBW in Crohns’ disease • Connective tissue disease

• Thrombophilia - 30% IUGR with APS • Cardiac disease • Smoking, alcohol, drug abuse, prescribed drugs • Malnutrition, ethnicity, assisted reproduction, AMA PAST OBSTETRIC HISTORY

Outcome of first Odds ratio for stillbirth Stillbirth rate per 1000 pregnancy, live births in second pregnancy births only (95 percent CI)

AGA, term 1.0 2.4

SGA, term 2.0 (1.5 to 2.6) 4.8

SGA, moderately 4.0 (2.5 to 6.3) 9.5 preterm

SGA, very preterm 8.0 (4.7 to 13.7) 19.0

Adapted from: Surkan, PS, Stephansson, O, Dickman, PW, Cnattingius, S. N Eng J Med 2004; 350:777. CLINICAL ASSESSMENT

• Accurate gestational age is critical – first trimester CRL is most accurate esp. <9/40 (margin of error +/- 5 days); between 9-14/40 margin of error +/- 7days • Symphysis-fundal height • Discordancy defined as >3cm from expected fundal height • Sensitivity for SGA 13-86% - sensitivity improved by having same clinician and unmarked side of tape and plotting on customised chart (24.8 vs 50.6%) • Abdominal palpation does not perform well (sensitivity 30-50%) • Ultrasound when risk factor present and/or concern on clinical assessment ULTRASOUND

• Sonographic estimation of fetal weight (using BPD, AC and FL) is single best test for SGA despite margin of error of ~15%, sensitivity 90%, specificity 85%, PPV 80%, NPV 90% • When US suggests SGA, referral for further evaluation to look for maternal, placental and fetal disorders recommended: • To separate constitutionally small but well fetus from IUGR, and • To guide further surveillance and management • AC is most specific indicator for SGA with sensitivity 61%, specificity 95%, PPV 86%, NPV 83%, better than HC, BPD or combination with either • Best performance at 34/40 and serial measurements >2 weeks apart RWH GUIDELINES

• Indications for fetal biometry at 28/40 and 36/40: • Prior pregnancy with FGR (recurrence risk ~25%) • Maternal medical disorders • Poorly controlled GDM • Tobacco and illicit substance misuse • Extremes of maternal age (<16 years, >40 years) • Single umbilical artery (risk of FGR ~15%) • Low PAPP-A <0.40 MoM • BMI >35kg/m2 at booking visit • Large multifibroid • Some women may require additional US 32/40 e.g. T1DM, T2DM, prev poor outcome, multiple risk factors, recurrent APH

US FEATURES OF CONSTITUTIONALLY SMALL FETUS

• Modest smallness (EFW 3-10th percentile) • Adverse outcome 6.2% EFW <3rd percentile vs 2% for EFW 3rd-10th percentile (PORTO trial) • Normal growth velocity across gestation • Normal physiology – normal AFI and Doppler studies • Adverse outcome 16% if combination EFW <3rd percentile and abn. UA Doppler (PORTO trial) • AC growth velocity above 10th percentile • Appropriate fetal size relative to maternal characteristics • Using biometric standards derived from group of white fetuses, ~15% of non-white fetuses classified growth restricted (<5th percentile) FURTHER EVALUATION OF SGA

• Fetal survey – 10% of IUGR is accompanied by congenital malformation; fetal echocardiogram is indicated if sonographer uncertain if heart is normal • Fetal genetic studies – consider if early (<24/40), severe (<3rd percentile), major structural abn., soft markers of aneuploidy • Screening for infection – TORCH, varicella (Others) MANAGEMENT PRINCIPLES

• Referral to appropriate hospital and team for confirmation of diagnosis, further evaluation and fetal surveillance (weekly initially) • Administer corticosteroids if <34/40 • Maternal interventions e.g. O2, bed rest, aspirin, heparin, etc., are ineffective • Timing of delivery: • Term (esp. if additional “soft marker” of IUGR e.g. , increased UA SDR) or features of acidosis/decompensation – deliver NOW • Features of hypoxia – increase frequency of surveillance and deliver if >34/40 • Intrapartum – continuous CTG monitoring, increased risk of CS or instrumental delivery • Future – aspirin significantly reduced incidence of IUGR in the presence of PET risk factors (OR 0.56); not advised without PET risk factors; heparin not effective

US AND CTG SURVEILLANCE OF THE GROWTH RESTRICTED FETUS INDICATIONS FOR DELIVERY

• Features of decompensation • Abnormal DV Doppler – absent of reversed a wave • Reversed end-diastolic flow on UA Doppler • Loss of brain-sparing (reduced PI) on MCA Doppler • Pulsatility on UV Doppler • Absent variability or late decelerations on CTG • (Grossly abn. BPP)

ROUTINE ULTRASOUND IN LATE PREGNANCY B R I C K E R L , MEDLEY N, PRATT JJ. COCHRANE DATABASE SYST REV. 2015 JUN 29;(6): C D 0 0 1 4 5 1 .

• OBJECTIVES - To assess the effects on obstetric practice and pregnancy outcome of routine late pregnancy ultrasound, defined as greater than 24 weeks' gestation, in women with either unselected or low-risk pregnancies. • MAIN RESULTS - There was no difference in antenatal, obstetric and neonatal outcome or morbidity in screened versus control groups. • Routine late pregnancy ultrasound was not associated with improvements in overall perinatal mortality. • CONCLUSIONS - Based on existing evidence, routine late pregnancy ultrasound in low-risk or unselected populations does not confer benefit on mother or baby. • There was no difference in the primary outcomes of perinatal mortality, preterm birth less than 37 weeks, caesarean section rates, and induction of labour rates if ultrasound in late pregnancy was performed routinely versus not performed routinely. REDUCED FETAL MOVEMENTS

• “” or maternal perception of fetal movements typically occur at 16-20 weeks, occurring earlier in parous women than nulliparous women • Frequency of fetal movements remain constant throughout 3rd trimester so reported “reduction” in FM in late pregnancy likely due to reduced intensity due to reduced room to move and more prolonged quiet periods • Decreased fetal movement is a common concern (74%) but under reported (~5%) and in those who report DFM, 51% waited >24 hrs • Cochrane review for kick counting shows insufficient evidence so maternal perception of DFM is still key • Significance of DFM – SB rate 13.9/1000 vs 3.5/1000; FGR <3rd percentile OR 2.18; preterm birth; low birth Apgar and acidaemia; fetomaternal haemorrhage • No evidence for “drink cold water”, “eat something sweet” or “call back later” • Increasing maternal and clinician awareness of DFM and changing attitudes on myths is key PATHOPHYSIOLOGY

• Normal quantity and quality of fetal movements ensures integrity of regulatory systems • When these regulatory systems are subjected to hypoxaemia, DFM is thought to be compensatory response as blood is diverted to essential organs PREGNANCY CARE AND MATERNAL EDUCATION

• Provide written information at time of booking in to the hospital and again at 28 week • Emphasise the importance of maternal awareness of fetal movements at every pregnancy visit • Advise women to contact their maternity care provider if they have concerns about decreased or absent fetal movement; tell them not to wait until the next day to report their concerns • Maternal concern overrides any definition of DFM based on the number of movements fel DFM BEFORE 28/40

• DFM between 24.0 and 27.6 weeks of gestation: If a woman presents with DFM between 24.0 and 27.6 weeks of gestation, confirm the presence of a fetal heartbeat by auscultation with a Doppler handheld device • If fetal movements have never been felt by 24 weeks of gestation, consider referring the woman to a specialist obstetrician DFM AT OR AFTER 28/40

• Women who are concerned about DFM should be advised to: • contact the hospital or qualified maternity care provider immediately • present within two hours for assessment if fetal movements are decreased or absent • Women who are concerned about reduced fetal movements should NOT be advised to: • wait until the next day for assessment • rest and monitor movements • drink iced water or have something to eat DFM MANAGEMENT FLOWCHART INITIAL ASSESSMENT

• the first priority is to confirm fetal heart immediately • CTG should be performed within two hours of presentation • if the presence of a fetal heart beat is not confirmed, arrange an urgent ultrasound scan to assess fetal cardiac activity ADDITIONAL ASSESSMENT

• Take a complete history: • Duration/pattern of DFM – is this the first occasion of DFM? • Maternal lifestyle issues e.g. exercise, smoking • Medication, alcohol or sedating drug use • Abdominal pain • Risk factors for stillbirth • Baseline maternal observations • Abdominal palpation • Consider AFI or fetal biometry within 24 hours; investigation for FMH

RISK FACTORS FOR STILLBIRTH

Previous reporting of DFM Alcohol or drug abuse Diabetes Trauma Extremes of maternal age Obesity FGR HT APH Smoking Placental insufficiency Primiparity Post-dates Ethnicity Rh isoimmunisation Genetic factors ONGOING CARE

• Research is limited but increased surveillance appropriate • Consumer leaflet “Your Baby’s Movements” • Consider expediting birth, particularly if: • where there is persistent maternal perception of DFM • where there are suspected/actual concerns for fetal wellbeing • A decision to expedite the birth needs to be weighed against the risks to the mother and baby at that particular gestation