Recurrence of clinical chorioamnionitis in subsequent pregnancies

OBJECTIVE: To establish the role of clinical chorioamnionitis as an independent risk factor for recurrence in a subsequent pregnancy. METHOD: This was a historical cohort study of pregnant women who had their first and second deliveries at our institution between January 1988 and May 2005. The index pregnancy was restricted to those who delivered vaginally. Data were collected from a continuously updated obstetric database and included demographic and labor characteristics and neonatal outcomes. Chorioamnionitis was diagnosed clinically. RESULTS: The study population consisted of 23,397 women. During the index pregnancy, 10% of women developed chorioamnionitis. This group was significantly different from the rest of the cohort in terms of age, ethnicity, length of labor, epidural analgesia, use of internal monitors, and incidence of prolonged rupture of membranes. In the second pregnancy, 6% of those women again developed chorioamnionitis compared with 2% of women who did not have chorioamnionitis in the first pregnancy (odds ratio 2.93, 95% confidence interval 2.40-3.57). After adjusting for the above confounders, the increased risk of recurrence persisted (odds ratio 1.85, 95% confidence interval 1.49-2.30). CONCLUSION: Women delivering vaginally who were diagnosed with chorioamnionitis during their first pregnancy are at increased risk for chorioamnionitis in a subsequent pregnancy. This supports the concept that there may be a predisposition to chorioamnionitis that should be further investigated.