P2.I170: Betamethasone Latency Period Does Not Affect Hypoglycemia Rate in Term Neonates

Background: Infants exposed to antenatal betamethasone (BMZ) between 34.0-36.6 weeks gestational age have increased risk for neonatal hypoglycemia, a known cause of brain injury. Risk of hypoglycemia is highest for infants born 12-72 hours after BMZ administration. Neonatal hypoglycemia in infants born at term (≥ 37 weeks) after BMZ has not been previously characterized. Term infants without additional risk factors such as growth restriction or maternal diabetes are not routinely screened and may be at risk for unrecognized neonatal hypoglycemia.

Methods: This retrospective cohort study analyzed maternal-infant dyads from the University of Minnesota Obstetric Measures database (January 2017-August 2023) who received BMZ during pregnancy and delivered at ≥ 37 weeks (N=758). Primary outcomes were neonatal hypoglycemia (glucose < 40 mg/dL) within 48 hours of birth, treatment for neonatal hypoglycemia (dextrose gel or IV dextrose), and likelihood of glucose screening in neonates exposed to BMZ < 14 days vs >14 days prior to delivery. Glucose screening was defined as the existence of one or more documented glucose values within 48 hours of birth. Demographics, pregnancy characteristics, neonatal characteristics and outcomes were summarized by time from last dose of BMZ to delivery. Odds ratios (OR) and 95% confidence intervals (CI) were obtained. Reported p-values are two-sided and a significance level of 0.05 was used.

Results: Of 758 maternal-infant dyads who met inclusion criteria, 161 received BMZ < 14 days prior to delivery and 597 received BMZ >14 days prior to delivery (Table 1). Maternal diabetes status did not differ between groups. The most likely indication for BMZ was pre-eclampsia/pregnancy-induced hypertension for those delivered < 14 days after BMZ, and preterm labor for those delivered >14 days after BMZ (p < 0.001). Median gestational age was 37.1 vs 38.4 for neonates born < 14 days vs >14 days after BMZ, respectively (p < 0.001). Birthweight was lower for infants delivered < 14 days after BMZ (3027 g vs 3280 g; p< 0.001), but the percentage of neonates classified as small for gestational age (SGA) or large for gestational age (LGA) did not differ between groups (p=0.756). Hospital length of stay was slightly longer for neonates delivered < 14 days after BMZ (2.1 vs 1.9 days, p=0.016). Odds of hypoglycemia, treatment for hypoglycemia and likelihood of glucose screening did not differ between groups (Table 2).

Conclusion: In this cohort of term neonates, a shorter latency period between BMZ administration and delivery was not associated with increased detection or treatment of hypoglycemia. However, the rate of hypoglycemia screening was low in both groups and rates of undiagnosed hypoglycemia in BMZ-exposed term neonates remain unknown. Prospective studies aimed at characterizing the risk of hypoglycemia in term neonates exposed to BMZ would be beneficial to inform hypoglycemia screening practices in BMZ-exposed term neonates.