Is there a benefit of antenatal corticosteroid when given < 48 h before delivery?

We assessed the association between a short antenatal corticosteroid administration-to-birth interval and neonatal outcome.

A retrospective study was conducted between 2010 and 2020. Eligible cases were singleton preterm live-born neonates born between 24-0/7 and 33-6/7 weeks of gestation and were initiated an ACS course of betamethasone. We divided the first 48 h following the first ACS administration to four time intervals and compared each time interval to those born more than 48 h following ACS administration. The primary outcome was a composite of adverse neonatal outcome, including neonatal mortality or any major neonatal morbidity.

A total of 200 women gave birth less than 48 h from receiving the first betamethasone injection, and 172 women gave birth within 2-7 days (48-168 h) from ACS administration. Composite adverse neonatal outcome was higher for neonates born less than 12 h from initial ACS administration compared to neonates born 2-7 days from the first betamethasone injection (55.45% vs. 29.07%, OR 3.45 95% CI [2.02-5.89], p value < 0.0001). However, there was no difference in composite adverse neonatal outcomes between neonates born 12-48 h following ACS administration and those born after 2-7 days. That was also true after adjusting for confounders.

12-24 h following ACS administration may be sufficient in reducing the same risk of neonatal morbidities as > 48 h following ACS administration. It may raise the question regarding the utility of the second dose of ACS.