Clinical Drug Experience Knowledgebase

A Randomized Placebo-Controlled Trial of Antenatal Corticosteroid Regimens

After the NICHD Consensus Development Conference in 1994, the antenatal administration of antenatal corticosteroids (betamethasone or dexamethasone) for prevention of death and the serious morbidities associated with preterm birth has become an accepted standard in American obstetric practice. Studies have shown that maximum beneficial effect occurs when the fetus is delivered within 7 days of antenatal steroid administration. The efficacy and safety of a single course of corticosteroids has been substantiated but it is unknown whether repetitive dosing has similar efficacy or what the maternal, fetal and neonatal risks are. Repeat courses of steroids are often administered. Two popular regimens exist for the patient who remains undelivered more than one week after initial therapy but who remains at risk for preterm birth. In one, steroids are repeated weekly until 34 weeks gestation, while in the other, steroids are only given once.

This multicenter trial is testing the safety and efficacy of weekly administration of antenatal steroids. Twenty four hundred women < 32.0 weeks gestation who are at risk for spontaneous preterm delivery and remain pregnant at least seven days after an initial course of corticosteroids are being randomized to either weekly courses of masked study drug (betamethasone or placebo) for 4 weeks or delivery, whichever comes first. Patients are asked about side effects at the weekly visits and samples of maternal blood at randomization and delivery are collected. Cord blood and placentas are also collected. Cranial ultrasounds are done on all neonates. On a subgroup of patients, an adrenocorticotrophic hormone (ACTH) stimulation test is being performed and an auditory brainstem response (ABR) performed. All infants attend a follow-up visit at 18 to 22 months corrected age where certified examiners, masked to study group assignment, collect physical and neurological data. The Bayley Scales of Infant Development will also be administered. A subgroup of infants will be seen at 36 months to administer the Intelligence scale from the McCarthy Scales of Children's Abilities.