The Impact of Maternal Obesity on Neonatal Outcomes of Pregnancies Complicated by Fetal Growth Restriction

Abstract

Objective This study aimed to characterize the relationship between maternal obesity, fetal abdominal size, and neonatal morbidity in pregnancies complicated by fetal growth restriction (FGR). Study Design Pregnancies complicated by FGR, which resulted in delivery of a live, singleton, nonanomalous infant at a single center between 2002 and 2013 were identified in a large, National Institutes of Health–funded database of detailed pregnancy and delivery information extracted by trained research nurses. Pregnancies complicated by diabetes were excluded. Fetal biometry measurements from third trimester ultrasounds performed at the same institution were extracted from another institutional database. Pregnancies were divided into cohorts based on fetal abdominal circumference (AC) gestational age percentile (<10th centile, 10–29th centile, 30–49th centile, and ≥50th centile) at the ultrasound closes to the date of delivery. Obesity was defined by prepregnancy body mass index >30 kg/m2. The primary outcome was a composite of neonatal morbidity (CM) including 5-minute Apgar < 7, arterial cord pH <7.0, sepsis, respiratory support, chest compressions, phototherapy, exchange transfusion, hypoglycemia requiring treatment, or neonatal death. Outcomes were compared between women with versus without prepregnancy obesity overall and then stratified by AC cohort. Results A total of 379 pregnancies met criteria; CM occurred in 136 (36%). Overall, there was no difference in CM between infants born to women with versus without obesity (risk ratio (RR): 1.11, 95% confidence interval: 0.79–1.56). When stratified according to AC at ultrasound closest to delivery, there was higher prevalence of CM occurring among women with prepregnancy obesity than those without prepregnancy obesity when the fetal AC was >50th or 30 to 49th centile However, these differences did not reach statistical significance. Conclusion Our study identified no significant difference in risk of CM among growth-restricted infants of obese versus nonobese mothers, including among infants with very small AC. More research is needed to further examine the potential relationships postulated here. Key Points