This April 2016 article in the New England Journal of Medicine raises lots of new and interesting questions as it answers some existing and important ones! The authors, on behalf of the NICHD, present results of an RCT giving antenatal betamethasone to women at high risk of late-preterm delivery (W34-W36) to see if this would lessen adverse respiratory events among these preterm newborns. Steroids are regularly given when early pre-term birth is expected, but the data has been unclear about what to do with the late pre-term pregnancies.

And it continues to be unclear! I love this study for its classic methodological elegance. Double-blind, randomized controlled trial; relatively large sample sizes (~1400 in each group); beautiful symmetry between groups; immediate and relevant primary and secondary outcomes.

And the results? I confess I’m not sure what to make of them. For mitigating the primary outcome (respiratory distress of a variety of different flavors, within 72 hours), the [tooltip tip=”The Number Needed to Treat (NNT) represents the predicted number of patients treated for one patient to see benefit. For example, if the NNT is 100, then–on average–out of one hundred patients treated, one is expected to receive the benefits of the therapy described in the trial.”]number needed to treat[/tooltip] (NNT) was 35, with a 95% confidence interval from 19 to 259. Various secondary outcomes had more clearly meaningful margins, and, as the authors (and Crowther & Harding’s commentary) point out, the best test will be in late follow up, several years from now. The authors point out one particularly interesting subgroup: there was a significantly meaningful reduction in risk in those patients for whom a cesarean delivery was planned. It would be interesting to see how the NNT played out in that group.

Overall, given a relatively mild adverse reaction profile (the authors note a need to follow the newborns for hypoglycemia) I am curious to see how this plays out in terms of recommended practice. Perhaps we’ll have to wait to see the long-term follow-up before we know, though I wouldn’t be surprised if this starts to become common practice in the c-section group sooner, at very least.

Gyamfi-Bannerman C, Thom EA, Blackwell SC, et al. Antenatal betamethasone for women at risk for late preterm delivery. N Engl J Med 2016;374:1311-1320 | PMID 26842679 [full article behind paywall]

Eager to hear your comments on the study! Please join the conversation.