Early Second-Trimester Fetal Growth Restriction and Adverse Perinatal Outcomes.

To estimate the risk of adverse perinatal outcomes among women with isolated fetal growth restriction from 17 to 22 weeks of gestation.

This was a retrospective cohort study of all singleton, nonanomalous pregnancies undergoing ultrasonography to assess fetal anatomy between 17 and 22 weeks of gestation at a single center from 2010 to 2014. After excluding patients with fetal structural malformations, chromosomal abnormalities, or identified infectious etiologies, we compared perinatal outcomes between pregnancies with and without fetal growth restriction, defined as estimated fetal weight less than the 10th percentile for gestational age. Our primary outcome was small for gestational age (SGA) at birth, defined as birth weight less than the 10th percentile. Secondary outcomes included preterm delivery at less than 37 and less than 28 weeks of gestation, preeclampsia, abruption, stillbirth, neonatal death, neonatal intensive care unit admission, intraventricular hemorrhage, need for respiratory support, and necrotizing enterocolitis.

Of 12,783 eligible patients, 355 (2.8%) had early second-trimester fetal growth restriction. Risk factors for growth restriction were African American race and tobacco use. Early second-trimester growth restriction was associated with a more than fivefold increase in risk of SGA at birth (36.9% compared with 9.1%, adjusted odds ratio [OR] 5.5, 95% CI 4.3-7.0), stillbirth (2.5% compared with 0.4%, OR 6.2, 95% CI 2.7-12.8), and neonatal death (1.4% compared with 0.3%, OR 5.2, 95% CI 1.6-13.5). Rates of indicated preterm birth at less than 37 weeks of gestation (7.3% compared with 3.3%, OR 2.3, 95% CI 1.5-3.5) and less than 28 weeks of gestation (2.5% compared with 0.2%, OR 10.8, 95% CI 4.5-23.4), neonatal need for respiratory support (16.9% compared with 7.8%, adjusted OR 1.6, 95% CI 1.1-2.2), and necrotizing enterocolitis (1.4% compared with 0.2%, OR 7.7, 95% CI 2.3-20.9) were also significantly higher for those with growth restriction. Rates of preeclampsia, abruption, and other neonatal outcomes were not significantly different.

Although fetal growth restriction in the early second trimester occurred in less than 3% of our cohort and most of those with isolated growth restriction did not have adverse outcomes, it is a strong risk factor for SGA, stillbirth, neonatal death, and indicated preterm birth.