The APPLe study: a randomized, community-based, placebo-controlled trial of azithromycin for the prevention of preterm birth, with meta-analysis

Abstract

Background: Premature birth is the major cause of perinatal mortality and morbidity in both high- and low-income countries. The causes of preterm labour are multiple but infection is important. We have previously described an unusually high incidence of preterm birth (20%) in an ultrasound-dated, rural, pregnant population in Southern Malawi with high burdens of infective morbidity. We have now studied the impact of routine prophylaxis with azithromycin as directly observed, single-dose therapy at two gestational windows to try to decrease the incidence of preterm birth.

Methods and findings: We randomized 2,297 pregnant women attending three rural and one peri-urban health centres in Southern Malawi to a placebo-controlled trial of oral azithromycin (1 g) given at 16-24 and 28-32 wk gestation. Gestational age was determined by ultrasound before 24 wk. Women and their infants were followed up until 6 wk post delivery. The primary outcome was incidence of preterm delivery, defined as <37 wk. Secondary outcomes were mean gestational age at delivery, perinatal mortality, birthweight, maternal malaria, and anaemia. Analysis was by intention to treat. There were no significant differences in outcome between the azithromycin group (n = 1,096) and the placebo group (n = 1,087) in respect of preterm birth (16.8% versus 17.4%), odds ratio (OR) 0.96, 95% confidence interval (0.76-1.21); mean gestational age at delivery (38.5 versus 38.4 weeks), mean difference 0.16 (-0.08 to 0.40); mean birthweight (3.03 versus 2.99 kg), mean difference 0.04 (-0.005 to 0.08); perinatal deaths (4.3% versus 5.0%), OR 0.85 (0.53-1.38); or maternal malarial parasitaemia (11.5% versus 10.1%), OR 1.11 (0.84-1.49) and anaemia (44.1% versus 41.3%) at 28-32 weeks, OR 1.07 (0.88-1.30). Meta-analysis of the primary outcome results with seven other studies of routine antibiotic prophylaxis in pregnancy (>6,200 pregnancies) shows no effect on preterm birth (relative risk 1.02, 95% confidence interval 0.86-1.22).

Conclusions: This study provides no support for the use of antibiotics as routine prophylaxis to prevent preterm birth in high risk populations; prevention of preterm birth requires alternative strategies.

Trial registration: Current Controlled Trials ISRCTN84023116

Figure 1. Trial profile.

Figure 2. Random effects meta-analysis of trials of routine antibiotic prophylaxis in pregnancy that report preterm birth <37 wk as outcome.