Are Newborn Outcomes Different for Term Babies Who Were Exposed to Antenatal Corticosteroids?

Abstract

Background Antenatal corticosteroids improve newborn outcomes for preterm infants. However, predicting which women presenting for threatened preterm labor will have preterm infants is inaccurate and many women receive antenatal corticosteroids but then go on to deliver at term. Objective The purpose of this study was to compare the short-term outcomes of infants born at term to women who received betamethasone (BMZ) for threatened preterm labor to infants who were not exposed to BMZ in utero. Study Design We performed a retrospective cohort study of infants born at or after 37 weeks’ gestational age (GA) to mothers diagnosed with threatened preterm labor during pregnancy. The primary neonatal outcomes of interest included transient tachypnea of the newborn (TTN), neonatal intensive care unit (NICU) admission, and small for gestational age (SGA), and were evaluated for their association with BMZ exposure while adjusting for covariates using multiple logistic regression. Results Of 5330 women, 1459 (27.5%) women received BMZ at a mean GA of 32.2±3.3 weeks. The mean age of women was 27±5.9 years-old and the mean GA at delivery was 38.9±1.1 weeks. Women receiving BMZ had higher rates of maternal comorbidities (P<0.001 for diabetes, asthma, and hypertensive disorder) and were more likely to self-identify as white (P=0.022). BMZ-exposed neonates had increased rates of TTN, NICU admission, SGA, hyperbilirubinemia, and hypoglycemia (all P-values <0.05). Controlling for maternal characteristics and GA at delivery, BMZ exposure was not significantly associated with diagnosis of TTN (aOR 1.10, 95% CI 0.80-1.51), though it was associated with more NICU admissions (aOR 1.49, 95% CI 1.19-1.86) and higher odds of the baby being small for gestational age (SGA, aOR 1.78, 95%CI 1.48 to 2.14). Conclusions Compared to women evaluated for preterm labor that did not receive BMZ, women receiving BMZ had infants with higher rates of NICU admission and SGA. While the benefits of BMZ to infants born preterm are clear, there may be negative impacts for infants delivered at term.