Diagnosis of mid-second trimester fetal growth restriction and associated outcomes

Abstract

Objective To evaluate maternal and neonatal outcomes of low-risk singleton pregnancies, without underlying maternal medical conditions or genetic and fetal anomalies associated with fetal growth restriction, that were diagnosed with fetal growth restriction (FGR) (EFW < 10th %) in the mid-second trimester (between 17 and 22 weeks and 6 days’ gestation). Methods A retrospective cohort study of all women who underwent a routine fetal anatomy ultrasound between 17 and 22 weeks and 6 days’ gestation at a community-based academic hospital was performed to identify subjects with an EFW <10th%. Pregnancies with inadequate dating, multiple gestations, preexisting maternal vascular disease (chronic hypertension and pregestational diabetes), lethal fetal anomalies, and abnormal prenatal genetic screening were excluded. Descriptive statistics were computed to describe the study population. Subjects were stratified into two groups, estimated fetal weight (EFW) <5th% and EFW 5th–9th%. The primary outcome was a small for gestational age neonate (SGA) at delivery. Secondary outcomes included a composite adverse neonatal outcome, perinatal death, hypertensive disorders of pregnancy, medically indicated delivery, and mode of delivery. A comparison of the two groups, EFW <5th% and EFW 5th–9th %, was performed. Continuous variables were compared utilizing Wilcoxon Rank Sum tests and categorical variables were compared using Fisher’s exact test or Chi-squared tests, and a dichotomous composite variable for adverse neonatal outcomes was also calculated. Results In total, 3,868 unique patient records were screened. Thirty-two patient records (0.8% of the total screened records) were eligible for inclusion. The primary outcome, SGA at delivery, occurred in 13/32 (41%) of the subjects. The secondary outcomes of the composite neonatal morbidity occurred in 9/32 (28%), hypertensive disorders of pregnancy in 10/32 (31%), and medically indicated delivery at <28 weeks gestation in 7/32 (22%) of the subjects. When comparing EFW <5th% and EFW 5th–9th%, EFW <5th% had a larger percentage of SGA newborns (66% vs. 25%, p = .02, OR = 8.0 95% CI 1.5–42.5). EFW <5th% was also significantly associated with a greater composite adverse neonatal outcome when compared to EFW 5th–9th% (54% vs. 10%, p = .015). The subgroup with an EFW <5th% also had higher rates of adverse outcomes including preeclampsia (42% vs. 10%, p = .073), abnormal umbilical artery Doppler studies (50% vs. 15%, p = .049), and medically indicated delivery <28 weeks (42% vs. 10%, p = .07). Conclusions Early onset FGR is a associated with high rates of SGA at delivery, as well as several adverse maternal and neonatal outcomes which include hypertensive disorders of pregnancy, a greater composite neonatal morbidity, perinatal death, and medically indicated preterm delivery. EFW <5th% was associated with worse outcomes when compared to those with an EFW 5th%–9th%.