Prophylactic antibiotics for inhibiting preterm labour with intact membranes

The contribution of subclinical genital tract infection to the aetiology of preterm birth is gaining increasing recognition, but the role of prophylactic antibiotic treatment in the management of preterm labour is uncertain. Since rupture of the membranes is an important factor in the progression of preterm labour, it is important to see if the routine administration of antibiotics confers any benefit, prior to membrane rupture.

To assess the effects of prophylactic antibiotics administered to women in preterm labour with intact membranes, on maternal and neonatal outcomes.

We searched the Cochrane Pregnancy and Childbirth Group's specialised register of controlled trials (May 2002), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2002), MEDLINE (1965 to May 2002). Other sources included contacting recognised experts and cross referencing relevant material.

Randomised trials which compared antibiotic treatment with placebo or no treatment for women in preterm labour (between 20 and 36 weeks' gestation) with intact membranes.

Standard methods of the Cochrane Collaboration and the Cochrane Pregnancy and Childbirth Group were used. Evaluation of methodological quality and trial data extraction were undertaken independently by the authors. Results are presented using relative risk for categorical data and weighted mean difference for continuous data.

This review has been updated (2002) to include data from the 'ORACLE II 2001' trial (six times larger than the previous 10 trials combined), which now dominates the results of this review. Meta-analysis of the 11 included trials (7428 women enrolled) shows a reduction in maternal infection with the use of prophylactic antibiotics (relative risk 0.74, 95% confidence interval 0.64 to 0.87) but fails to demonstrate a benefit or harm for any of the prespecified neonatal outcomes.

This review fails to demonstrate a clear overall benefit from prophylactic antibiotic treatment for preterm labour with intact membranes on neonatal outcomes and raises concerns about increased neonatal mortality for those who received antibiotics. This treatment cannot therefore be currently recommended for routine practice. Further research may be justified (when sensitive markers for subclinical infection become available) in order to determine if there is a subgroup of women who could experience benefit from antibiotic treatment for preterm labour prior to membrane rupture, and to identify which antibiotic or combination of antibiotics is most effective.