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January 7, 1998

Premature Rupture of Membranes, Antibiotics, and Amnionitis—Reply

Author Affiliations

Margaret A.WinkerMD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Senior EditorIndividualAuthor

JAMA. 1998;279(1):22. doi:10.1001/jama.279.1.17

In Reply.—In response to Dr Cooperstock, we have evaluated the potential circadian nature of PPROM in our study population. We found PPROM to be equally common between midnight and 7:59 AM (34.7%), 8 AM and 3:59 PM (33.1%), and 4 PM and 11:59 PM (32.2%). Because antibiotic therapy has been demonstrated to reduce the incidence of clinical amnionitis, we analyzed those patients randomized to placebo further to determine the frequency of amnionitis based on hour of membrane rupture. As demonstrated by Cooperstock,1 we found a significant variation in the incidence of amnionitis with time of membrane rupture (P=.03). Clinically diagnosed amnionitis was less frequently identified between midnight and 7:59 AM (22.8%) than between 8 AM and 3:59 PM (39.4%) and between 4 PM and 11:59 PM (35.9%). While the majority of women who developed amnionitis did so during the 16 hours between 8 AM and 11:59 PM, 29% of women who developed amnionitis had membrane rupture between midnight and 7:59 AM. The discriminative value of time of membrane rupture for prediction of amnionitis is poor. Logistic regression analysis of clinical amnionitis, based on time of membrane rupture and group B streptococcus culture status (carriers treated before and during labor), among those gravidas receiving study antibiotics, revealed no significant association between time of membrane rupture and clinical amnionitis. This suggests that although there is a circadian character to the incidence of amnionitis after PPROM, the time of membrane rupture is not useful in predicting amnionitis among those receiving antibiotics.