Neonatal morbidity in late preterm small for gestational age neonates

To compare neonatal respiratory morbidity among small for gestational age (SGA; birth weight less than 10th percentile for gestational age) versus appropriate for gestational age (AGA; BW at 10-90th percentile) neonates born in the late preterm period.

A secondary analysis of a multicenter randomized trial of antenatal corticosteroids for women at risk for late preterm birth. Singleton, nonanomalous, AGA or SGA births that delivered at 34-36 weeks were included. Women were excluded if they delivered after 37 weeks or had a large for gestational age baby (LGA; weight over 90th for gestational age). The primary outcome was a composite of any of the following: respiratory support by 72 h (continuous positive airway pressure or high flow nasal cannula ≥2 h, oxygen with a fraction of inspired oxygen of ≥30% for ≥4 h, extra corporeal membrane oxygenation or mechanical ventilation) or neonatal death. The secondary outcomes included several neonatal and maternal morbidities. Multivariable Poisson regression models were used to examine the association between neonatal weight and outcomes (using adjusted relative risk [aRR] and 95% confidence intervals [CI]).

Of the 2831 women in the parent trial, 2315 (82%) women met inclusion criteria; among them, 426 (18%) of the neonates were SGA. There was no significant difference in the risk of the primary outcome between SGA and AGA (13.1 versus 15.1%, aRR 0.85, 95% CI 0.66-1.10). SGA, however, was associated with an increased risk for neonatal intensive care unit admission (68 versus 45%, aRR 1.60, 95% CI 1.47-1.74), hypothermia (12.2 versus 8.8%, aRR 1.36, 95% CI 1.01-1.83), feeding problems (47.2 versus 36.9%, aRR 1.24, 95% CI 1.07-1.45) and a decreased risk of neonatal hyperbilirubinemia (7.5 versus 12.7%, aRR 0.59, 95% CI 0.41-0.84), when compared to AGA.

In this cohort of late preterm birth, there was no significant difference in the rate of composite respiratory morbidity between SGA and AGA newborns.