The case for tocolysis in threatened preterm labour

Area of Science:

• Perinatology
• Neonatal Medicine
• Pharmacology

Background:

• Placebo-controlled trials of tocolytics have failed to demonstrate improved neonatal outcomes.
• This failure is often misinterpreted as ineffectiveness, overlooking suboptimal trial designs and patient selection.
• Previous studies did not exploit the gained time for neonatal optimization or use adequate power to detect small but clinically meaningful differences.

Purpose of the Study:

• To re-evaluate the effectiveness of tocolytics in improving neonatal outcomes.
• To analyze the impact of tocolytic therapy on specific neonatal morbidities and survival rates.
• To identify factors influencing the perceived efficacy of tocolytics and suggest future research directions.

Main Methods:

• Bayesian interpretation of existing placebo-controlled trial data.
• Meta-analysis of neonatal morbidity in beta-agonist trials.
• Meta-analysis of comparative trials of calcium antagonists versus beta-agonists.

Main Results:

• Bayesian analysis suggests tocolytics do improve neonatal outcomes.
• Trends towards better survival in fetuses <28 weeks, lower cerebral palsy rates, and higher Bayley scores were observed.
• Meta-analysis indicated a near-significant reduction in respiratory distress syndrome (RDS) with beta-agonists and significantly lower RDS and jaundice with calcium antagonists compared to beta-agonists.

Conclusions:

• Tocolytics may be effective, but previous trials were underpowered and poorly designed.
• Calcium antagonists show promise in reducing neonatal respiratory distress syndrome and jaundice.
• Future adequately-powered, placebo-controlled studies focusing on high-risk pregnancies are needed to confirm efficacy and optimize use.