Perinatal Outcomes With Normal Compared With Elevated Umbilical Artery Systolic-to-Diastolic Ratios in Fetal Growth Restriction

OBJECTIVE:To compare the composite neonatal morbidity of pregnancies with fetal growth restriction (estimated fetal weight less than the 10th percentile) and normal compared with elevated umbilical artery systolic-to-diastolic ratios. METHODS:This was a retrospective cohort study of all pregnancies complicated by fetal growth restriction with normal compared with elevated umbilical artery systolic-to-diastolic ratios from January 2008 to July 2012 at a single center. Exclusions were multiple gestation, prenatally diagnosed fetal anomalies, delivery at outside institution, and absent or reversed end diastolic flow. Maternal characteristics and perinatal outcomes including composite neonatal morbidity were compared between groups. RESULTS:Of 11,785 pregnancies evaluated, 789 (7%) were diagnosed with fetal growth restriction. Among 512 that met inclusion criteria, 394 (77%) had normal and 118 (23%) had elevated umbilical artery systolic-to-diastolic ratios. When fetal growth–restricted pregnancies with elevated umbilical artery systolic-to-diastolic ratios were delivered at 37 weeks of gestation were compared with those with normal umbilical artery systolic-to-diastolic ratios delivered at 39 weeks of gestation, there was no difference in the rate of neonatal intensive care unit admission (101 [25.7%] compared with 51 [43.2%]; crude odds ratio [OR] 2.5, 95% confidence interval 1.5–4.0; adjusted OR 1.37, 95% CI 0.69–2.71) or composite neonatal morbidity (60 [15.2%] compared with 24 [20.3%]; crude OR 1.42, 95% CI 0.84–2.40; adjusted OR 0.91, 95% CI 0.45–1.84). CONCLUSION:Composite neonatal morbidity is comparable in fetal growth–restricted pregnancies with elevated compared with normal umbilical artery systolic-to-diastolic ratios when delivered at 37 and 39 weeks of gestation, respectively. Planning delivery of pregnancies with fetal growth restriction and elevated systolic-to-diastolic ratios and without other complications at 37 weeks of gestation results in good outcomes. LEVEL OF EVIDENCE:II