509: The association between fetal growth trajectories and adverse neonatal outcomes in a preterm population

Abstract

Customized fetal growth trajectories have been suggested as an alternative to arbitrary thresholds to identify pathologically growth-restricted fetuses (FGR). The objective of this study was to estimate the risk of adverse neonatal outcomes using fetal growth trajectories in the preterm neonate. This is a retrospective cohort study of non-anomalous singleton gestations that underwent a mean of three ultrasounds in our unit between 20-40 weeks gestation from 2008-2015. Growth trajectories were created from estimated fetal weights (EFW) using growth mixture models. Fetuses were classified as having either decelerated, normal or accelerated growth trajectories. Analysis was limited to fetuses delivered between 28-36 weeks that were admitted to the neonatal intensive care unit. The primary outcome was a composite neonatal morbidity. Secondary outcomes included actual birth weight (BW), 5 minute Apgar scores, and respiratory distress syndrome (RDS). Univariate and multivariate logistic regression analyses were used to estimate the risk of adverse neonatal outcomes across fetal growth trajectories. Of 355 fetuses, growth trajectories were identified as decelerated in 46.5%, normal in 49.3% and accelerated in 4.2%. Compared to fetuses with normal growth, fetuses with decelerated growth had an increased risk of having an actual BW<10th percentile, actual BW<5th percentile and 5 minute Apgar score <7. (Table) After adjusting for gestational age at the time of delivery, a decelerated fetal growth trajectory was significantly associated with an increased risk for the composite adverse neonatal outcome (aOR 1.7, 95% CI 1.1-2.9). Only 12.7% of patients with a decelerated growth trajectory would have been identified as FGR by EFW<10th percentile at the last ultrasound prior to delivery. A decelerated fetal growth trajectory is associated with an increased risk for adverse neonatal outcomes in a preterm population. This approach may more accurately identify fetuses with abnormal growth which ultimately may influence patient counseling and fetal surveillance.