Azithromycin Prophylaxis for PRElabor CEsarean DElivery Trial

Inclusion Criteria: * ≥ 23 weeks' gestation (ACOG dating criteria) * Scheduled or prelabor cesarean delivery * Singleton or twin gestation Exclusion Criteria: * Allergy or contraindication to azithromycin or macrolide antibiotics, including those with a history of cholestatic jaundice/hepatic dysfunction associated with prior use of azithromycin * Chorioamnionitis * Bacterial infection (e.g., pyelonephritis) requiring ongoing antibiotic treatment after delivery * Premature rupture of membranes (PROM) or labor (i.e., contractions with ongoing cervical change) * Fetal demise or known major congenital anomaly * Azithromycin treatment within 7 days * Planned use of antimicrobial prophylaxis after delivery for any reason * Known structural heart disease or active cardiomyopathy (current ejection fraction\<40%) * Known arrhythmia with QT prolongation or taking scheduled medications known to prolong the QT interval such that it would preclude the use of azithromycin * Refusal or unable to obtain consent (e.g., language barrier) * Participating in another intervention study that influences the primary outcome in this study * Participation in this trial in a previous pregnancy. Patients who were screened in a previous pregnancy, but not randomized, do not have to be excluded.