Dose Reduction of Antenatal Betamethasone Given to Prevent the Neonatal Complications Associated With Very Preterm Birth

Overview

Extensive animal studies have indicated that antenatal betamethasone exposure results in altered developmental trajectories of several fetal systems. Follow up of a randomized controlled trial has shown that antenatal betamethasone exposure might result in insulin resistance 30 years later. Furthermore, animal studies and randomized trials in Humans have clearly demonstrated that betamethasone-induced growth alterations were dose-related. In ewes, a 50% reduced dose regimen resulted in maximal improvement in preterm lamb lung function, similar to those obtained after a full dose. Our hypothesis is that antenatal betamethasone after a 50% dose reduction, justified by the potential long term effects of this drug, is not inferior to a full dose to promote fetal lung maturation in Humans.

The BETADOSE project consist in a randomized, multicenter, double blind placebo-controlled non inferiority trial comparing a standard dose regimen (24 mg) to a reduced dose regimen (12 mg) of betamethasone given to prevent the neonatal complications associated with very preterm birth.A betamethasone course consists in 2 injections of 12 mg betamethasone 24 hours apart for a total dose of 24 mg. The first injection will be unmasked in both group. In both group, women will receive a first 12 mg injection of betamethasone according to local protocols. Randomization will be performed after the first injection. Women will then receive either a placebo injection (reduced dose regimen, 12 mg only from the first injection) or a second 12 mg betamethasone injection (standard dose regimen, 12 mg from the first injection and 12 mg from the second injection=24 mg). This protocol allows women sent from level 1 and 2 to level 3 perinatal centers after having already received their first injection to participate. In case of multiple antenatal betamethasone courses, women will receive their second course according to the same design as in their first course.