The effect of prophylactic antibiotics prior to catheter balloon insertion on clinical chorioamnionitis in GBS-colonized term pregnancies

Objective: To compare the risk of clinical chorioamnionitis at delivery among patients with Group B Streptococcus (GBS) colonization undergoing induction of labor (IOL) with catheter balloon insertion, according to two protocols. Methods: We conducted a retrospective cohort study of patients with term singleton pregnancies undergoing IOL for medical indications at two tertiary centers. At Galilee Medical Center, positive GBS colonization prompted intravenous ampicillin (2 g every 6 h) starting 30 min prior to catheter balloon insertion and continued until delivery (early antibiotic prophylaxis group). At Tzafon Medical Center, antibiotics were administered according to standard guidelines at the onset of active labor or rupture of membranes (routine intrapartum antibiotic prophylaxis (IAP) group). The primary outcome was clinical chorioamnionitis. Secondary outcomes included postpartum infectious morbidity, delivery mode, and neonatal outcomes. Results: Of 144 patients, 75 received early prophylactic antibiotics and 69 received routineIAP. Baseline maternal and obstetric characteristics were comparable. For the early prophylactic antibiotics vs. the routine IAP group, prevalences were lower of clinical chorioamnionitis (0.0 % vs. 8.7 %, p = 0.002) and maternal fever (2.7 % vs. 15.9 %, p = 0.005). Statistically significant differences were not observed in postpartum infections, cesarean delivery rates (16.0 % vs. 26.1 %, p = 0.136), or neonatal outcomes. On multivariate analysis, routine IAP administration compared with early prophylactic antibiotics was independently associated with an increased risk of clinical chorioamnionitis (adjusted odds ratio 9.43, 95 % confidence interval 1.66-53.45, p = 0.01). Conclusion: Prophylactic antibiotics administered prior to catheter balloon insertion in patients with GBS colonization were associated with a lower risk of clinical chorioamnionitis.