In Reply:

Résumé fourni par la source

In Reply: We thank the authors for their interest in our research, published in the April 2024 issue, and their insightful comments.1 The authors provide theoretical explanations regarding differences between betamethasone phosphate and combination betamethasone acetate and phosphate to explain disparity in outcome between our study and the ALPS trial (Antenatal Late Preterm Steroids).2 However, there are no data to support this hypothesis. The peak plasma concentration of betamethasone is reached by 12 hours, whereas betamethasone acetate acts as a reservoir for sustained action.3 The time of maximum plasma concentration is the same for both, which is 3 hours, although the combination has a multiphasic concentration that lasts for up to 2 weeks or more.4 In women in whom preterm labor is inevitable, the preferred drug of choice is one with quick onset of action, and prolonged steroid exposure is undesirable. We would like to reinforce that differences in population characteristics and management strategies are likely the major contributors to the differences in the outcome, rather than the composition of the drug. In our trial, 60% of women had received both doses of antenatal corticosteroids, and the average duration between last dose and delivery was 6 days, wherein the maximum effect is expected.5 With regard to sample size calculation, using the software quoted by the authors, the number needed in each arm was 559, which is similar to our sample size of 555. The negligible difference of 4 is due to the way different software programs calculate and round up sample size. The authors contend and mention sample size as 659 in each arm, which we assume is a typographical error. The efficacy of antenatal corticosteroids in multiple gestations is controversial. No studies have confirmed its benefits,6 and recommendations are extrapolated from the efficacy seen in singleton gestations. We did not want to exclude multiple gestations, because this is a major cause of preterm delivery and its associated morbidity. Our study protocol amendment for inclusion of twins was approved by our IRB and monitored by the Data Safety Monitoring Board, negating the possibility of publication bias. Also, analysis among singleton gestations found no statistical significance in the primary outcome.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.