OP32.08: Management of fetal growth restriction at ≥ 36 weeks of gestation: what can be achieved by careful fetal monitoring?

Abstract

Background: Fetuses with diagnosed growth restriction are increasingly delivered by caesarean section.We hypothesised that an attempt of vaginal delivery is feasible and aimed to evaluate the maternal and neonatal outcome in fetal growth restriction (FGR) according to prenatal blood flow measurements. Methods: Retrospective observational study on singleton pregnancies with gestational age >36 + 0 weeks and a birthweight <5th centile during a five year period (2004-2008) at Haukeland University Hospital. The blood flow pulsatility index (PI) was measured in a free loop of the umbilical artery (UA) and in the middle cerebral artery (MCA). The cerebral placental ratio (CPR) was calculated dividing the MCA-PI by the UA-PI. An UA-PI >95th, MCA-PI <5th and CPR <5th centiles were defined as abnormal. Only the last blood flow measurement before delivery was included into the analysis. Neonates with a birthweight between the 10th and 90th centile constituted the reference population (N = 17861). Results: Out of 1157 growth restricted neonates, 370 (32%) were identified prenatally. In this group 281/370 (77%) had a vaginal delivery, while 18 (5%) and 71 (19%) were delivered by elective and emergency caesarean section, respectively. The perinatal mortality in cases with prenatally diagnosed FGR was 7/370 (1.9%) including 4 cases with lethal malformations or chromosomal abberations and 3 cases of antepartum stillbirth. Cord artery metabolic acidosis occurred in 3/211 (1.4%). There were no cases of moderate or severe neonatal encephalopathy. Blood flow was abnormal in 49/324 (15%) and 62/228 (27%) of the available UA- and MCA-PI measurements, respectively. An abnormalCPR was calculated in 87/225 (39%). A total of 36/87 (41%) of FGR fetuses with abnormal CPR had a caesarean delivery compared to 30/138 (22%) with normal CPR and 8% in the reference population. There was a positive linear relationship between CPR z scores and cord oxygen partial pressure of the UA and vein at delivery and a negative relationship between CPR z scores and CO2 partial pressure of the umbilical vein. An abnormal CPR was associated with increased risk of emergency caesarean section (OR 8.1 95%CI 5.2-12.7) and transfer to the neonatal intensive care unit (OR 6.7, 95% CI 3.9-11.5), but neither cord artery acidosis (pH < 7.15) (OR 0.7, 95% CI 0.3-1.7) nor 5 min Apgar score <7 (OR 1.4, 95% CI 0.2-9.7). Conclusion: Provided careful fetal monitoring vaginal delivery could be achieved in the majority of cases without risk of severe neonatal morbidity. Prenatal diagnosis of FGR at >36 weeks of gestation allowed for further risk-assessment by Doppler ultrasound. Fetal circulatory compromise was reflected by cord hypoxemia at delivery