To measure the effect of prophylactic antibiotics given at time of previable prelabor rupture of membranes (PROM) on latency. Single center, retrospective cohort study of singleton pregnancies with previable (<23 0/7weeks) PROM. Antibiotics were given at clinician discretion. The primary outcome was latency, defined as duration of time between previable PROM and delivery. Secondary outcomes included delivery at ≥ 23weeks, infant survival, and maternal morbidity. Bivariate analysis compared maternal covariates between women who did and did not receive antibiotics. Antibiotic effect on latency was modeled using a Cox proportional hazards ratio. 213 women with previable PROM were identified; 77 (36%) remained pregnant and thus were included in this analysis. Forty (52%) of 77 received antibiotics. Compared to women who did not receive antibiotics, those who did had PROM at a later median (IQR) estimated gestational age, EGA, (22.2weeks [20.7, 22.5] vs. 19.3weeks [18, 20.7], p < 0.01). Median (IQR) latency was not different between women who did and did not receive antibiotics (2.2 [0.7, 3.9] vs. 1.5 [0.5, 4.6] weeks, p = 0.49). More infants survived to discharge among women who received antibiotics compared to those who did not [17(43%) vs. 3(8%), p < 0.01]. When adjusted for EGA at PROM, antibiotics were associated with longer latency (HR 0.57 [95% CI 0.33, 0.97], p = 0.01). Antibiotic use was not associated with differences in maternal morbidity. After adjusting for EGA at PROM, antibiotic receipt was associated with longer latency. Larger prospective studies are needed to define the utility of prophylactic antibiotics in previable PROM.