Birmingham, AL—While the use of azithromycin is known to reduce maternal infection in women during unplanned cesarean delivery, it has remained unclear if antibiotic therapy is beneficial to women with planned vaginal delivery.

That is why a new international study sought to determine if an intrapartum oral dose of azithromycin would reduce maternal and offspring sepsis or death.

In the University of Alabama Birmingham–led, placebo-controlled, randomized trial, researchers assigned women who were in labor at 28-weeks’ gestation or more and who were planning a vaginal delivery to receive a single 2-g oral dose of azithromycin or placebo.

For the trial reported in the New England Journal of Medicine, 29,278 women underwent randomization. The two primary outcomes were defined as a composite of maternal sepsis or death and a composite of stillbirth or neonatal death or sepsis. The study team pointed out that during an interim analysis, the data and safety monitoring committee recommended stopping the trial for maternal benefit.

The results indicated that the incidence of maternal sepsis or death was lower in the azithromycin group than in the placebo group (1.6% vs. 2.4%), with a relative risk (RR) of 0.67 (95% CI; 0.56-0.79, P <.001), but the incidence of stillbirth or neonatal death or sepsis was similar (10.5% vs. 10.3%), with an RR of 1.02 (95% CI; 0.95-1.09, P = .56). “The difference in the maternal primary outcome appeared to be driven mainly by the incidence of sepsis (1.5% in the azithromycin group and 2.3% in the placebo group), with a relative risk of 0.65 (95% CI, 0.55-0.77); the incidence of death from any cause was 0.1% in the two groups (relative risk, 1.23; 95% CI, 0.51-2.97),” the researchers advised.

The study found that neonatal sepsis occurred in 9.8% of the infants in the azithromycin group and 9.6% of the placebo group (RR 1.03; 95% CI, 0.96-1.10). “The incidence of stillbirth was 0.4% in the two groups (RR 1.06; 95% CI, 0.74-1.53); neonatal death within 4 weeks after birth occurred in 1.5% in both groups (RR 1.03; 95% CI, 0.86-1.24),” the study noted. “Azithromycin was not associated with a higher incidence in adverse events.”

The authors concluded that for women planning a vaginal delivery, a single oral dose of azithromycin resulted in a significantly lower risk of maternal sepsis or death than placebo but had little effect on newborn sepsis or death.

“The frequencies of selected maternal infections that cause sepsis (including endometritis, cesarean or perineal wound infections, and pyelonephritis), maternal readmissions, and unscheduled healthcare visits were consistent with the primary maternal results,” the authors wrote. “Findings for individual neonatal outcomes mirrored those for the primary neonatal outcome. The number of women who would need to be treated to prevent one case of maternal death or sepsis was 125; the same number would need to be treated to prevent one maternal sepsis event.”

Previous research in the United States found that the use of azithromycin resulted in a lower incidence of maternal infections, including a 50% lower risk of endometritis and wound infections, than with the use of placebo. It also was associated with fewer readmissions or unscheduled care visits, although outcomes for newborns were not affected.

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