238: Do hypertensive disorders affect neonatal mortality rates in SGA neonates?

Abstract

Fetal growth restriction (FGR) and small size for gestational age at birth (SGA) are associated with an increased risk of fetal/neonatal mortality. A key element of FGR management is the comparison of expected mortality with expectant management vs. iatrogenic delivery. Further complicating this challenge, maternal hypertensive disorders (chronic hypertension, gestational hypertension, preeclampsia) are often associated with FGR, introducing additional concerns for maternal well-being. Notwithstanding maternal risks, the approach to fetal surveillance is comparable for FGR pregnancies with or without HTN. We sought to determine if neonatal mortality differed in FGR/SGA pregnancies with or without HTN. We used multivariate logistic regression to compare rates of neonatal death (NND) at specific gestational ages in FGR/SGA pregnancies with or without maternal HTN. FGR/SGA was defined as a fetal/neonatal weight <10% by Fenton nomogram. In 3 distinct analyses, we compared rates of NND in pregnancies identified at Magee-Womens Hospital from 2000-2015 with FGR by ultrasound (MWH-US; 1,097 FGR, 258 with HTN, 34 NNDs), with SGA birthweight (MWH-BW; n=8,267, 1,537 HTN, 81 NND), and all deliveries from 2005-2009 US Vital Statistics with SGA birthweight (National-BW; n=1,358,191, 84,598 HTN, 11,427 NND). NND rates were consistently lower for FGR/SGA neonates born to mothers with HTN than for FGR/SGA neonates without HTN [MWH-US Odds Ratio 0.26 (95% C.I. 0.10, 0.68); MWH-BW OR 0.20 (0.10, 0.37); National-BW OR 0.36 (0.33, 0.39)]. Predicted probabilities of NND with and without HTN at specific gestational ages are shown graphically. Gestational-age adjusted NND rates were lower for FGR/SGA pregnancies with HTN than for FGR/SGA pregnancies without HTN. This finding may be attributable to the fact that FGR with HTN is more likely to lead to iatrogenic premature delivery without a fetal indication due to concerns for maternal health. Nonetheless, with the observed effect of HTN on neonatal mortality, estimates of risk with expectant management vs. iatrogenic delivery in FGR pregnancies may be more accurate with adjustment to reflect the presence or absence of HTN.