To evaluate whether the use of ampicillin and azithromycin leads to a similar latency period in preterm premature rupture of membranes as ampicillin and erythromycin and whether the substitution of azithromycin for erythromycin effects rates of other outcomes.
We performed a retrospective cohort study of women with preterm premature rupture of membranes between 24 and 34 completed weeks of gestation and compared two groups: those who received ampicillin and erythromycin and those who received ampicillin and azithromycin. Primary outcome was length of latency (defined as time from first antibiotic dose to delivery) and secondary outcomes were rates of chorioamnionitis, cesarean delivery, Apgar scores, birth weight, neonatal death, neonatal sepsis, and neonatal respiratory distress syndrome.
Of 168 women who met inclusion criteria, 75 received ampicillin and erythromycin and 93 received ampicillin and azithromycin. There was no difference in latency between groups: 9.6±13.2 days (erythromycin) compared with 9.4±10.0 (azithromycin) days (P=.40). Secondary outcomes did not differ between groups. We had 80% power to detect a difference of 5 days.
Among women with preterm premature rupture of membranes between 24 and 34 completed weeks of gestation, substitution of azithromycin for erythromycin in the recommended antibiotic regimen did not affect latency or any other measured maternal or fetal outcomes.
There is no difference in latency when azithromycin and ampicillin are substituted for erythromycin and ampicillin in patients with preterm premature rupture of membranes.
Indiana University School of Medicine and Department of Medicine, Division of Clinical Pharmacology, and Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana.
Corresponding author: David M. Haas, MD, MS, Department of Obstetrics and Gynecology, 550 N University Boulevard, UH 2440, Indianapolis, IN 46202; e-mail: email@example.com.
Supported by PREGMED: The Indiana University Center for Pharmacogenetics and Therapeutics Research in Maternal and Child Health (5U01HD063094) (D.M.H.) and National Institutes of Health–National Institute of General Medical Sciences: Indiana University Comprehensive Training in Clinical Pharmacology (2T32GM008425-21) (R.C.P.).
Financial Disclosure The authors did not report any potential conflicts of interest.