OBJECTIVE: To evaluate clinical, microbiologic, and histologic findings associated with elevated C-reactive protein levels among women in preterm labor or with preterm premature rupture of the membranes (PROM). METHODS: Obstetric data, serum C-reactive protein levels, and amniotic fluid (AF) and chorioamniotic membrane cultures and histology were obtained on 203 women presenting between 22-34 weeks' gestation in preterm labor or with PROM. RESULTS: Women with C-reactive protein greater than 1.5 mg/dL were more likely to deliver within 7 days of enrollment (54 of 68, 79%) than were women with normal C-reactive protein levels (45 of 135, 33%) (P