Multiple Courses of Antenatal Corticosteroids for Preterm Birth

Abstract

a single course of antenatal corticosteroids (ACS) reduces the risks of neonatal death, respiratory distress syndrome (RDS) and possibly intraventricular haemorrhage (IVH) in preterm infants. Because the maximum benefit of therapy appears to occur between 24 hours and seven days following the initial treatment, some physicians have suggested that repeated courses of ACS be administered at weekly intervals to women who remain at increased risk of preterm delivery. In some centres, this approach has become routine, despite the fact that repeated courses of ACS have not been evaluated in a randomized fashion. There are limited numbers of small human studies which have reported that multiple courses of ACS are associated with a decreased risk of RDS. They also have reported a slightly higher risk of necrotizing enterocolitis (NEC) and neonatal mortality, and a reduction in birth head circumference and birthweight. In animals, multiple courses of ACS have been associated with a progressive improvement in post-natal lung function. However, infant growth restriction and alteration of central nervous system myelination have also been shown as adverse effects. The Multiple Courses of Antenatal Corticosteroids for Preterm Birth Study (MACS) has been proposed as a multicentre, double-blind, randomized controlled trial of multiple courses versus a single course of ACS for women at increased risk of preterm birth. Centres in Canada, the USA and Israel have been invited to participate. Prior to MACS, a pilot study will be undertaken at Sunnybrook and Women’s College Health Science Centre and Mount Sinai Hospital in Toronto, to determine the feasibility of MACS.