BACKGROUND: Threatened preterm labor complicates annually 20,000 deliveries in The Netherlands. While tocolysis
historically is a cornerstone of the treatment, the effectiveness of this treatment has never been proven.
OBJECTIVE: To compare the effectiveness of the tocolytic agent atosiban to placebo for threatened preterm labor between 30 and 34 weeks gestation.
STUDY DESIGN: Multicenter randomized double-blind placebo-controlled trial.
STUDY POPULATION: Pregnant women with threatened preterm labor between 30 and 34 weeks gestational age.
INTERVENTION: Atosiban vs placebo.
SAMPLE SIZE CALCULATION: A difference in a composite for poor neonatal outcome from 10% to 6% (beta 0.2, alpha 0.05) can be detected if 1,438 patients are recruited. Accounting for a potential 5% loss to follow up we plan to randomise 1,514 women.
MAIN OUTCOME MEASURES: The primary outcome of the study will be a composite for poor neonatal outcome. Secondary outcomes will be birth within 48 h, time to delivery, gestational age at delivery, number of days on ventilation support, length of admission in Neonatal Intensive Care Unit, convulsions, apnea, asphyxia, proven meningitis, pneumothorax and total days alive outside the hospital until three months corrected age, maternal morbidity, side effects and costs.
ECONOMIC EVALUATION: We will perform an economic analysis alongside the study, in which we will calculate the additional cost per prevented case of adverse perinatal outcome for atosiban compared to placebo.