Chorioamnionitis: its association with pregnancy outcome and microbial infection

In a study of 33 cases of perinatal death, chorioamnionitis was observed in 57.6% compared with 5% of 20 control cases (p less than 0.001) and in 70.8% of cases with no morphologic cause compared with 22.2% of cases with a defined cause of death (p less than 0.01). Chorioamnionitis was significantly associated with previous gestations (p less than 0.01), prolonged rupture of the membranes (p less than 0.001), prematurity (20 to 27 weeks' gestation) (p less than 0.001), and low birth weight (less than or equal to 1000 gm) (p less than 0.001) but not with elevated maternal white blood cell count or pyrexia. Overall, in patients with chorioamnionitis, the perinatal death rate was higher (p less than 0.01); more stillbirths occurred compared with early neonatal deaths (p less than 0.05), and there was a higher incidence of deaths with no defined cause (p less than 0.01) compared with cases without chorioamnionitis. Ureaplasma urealyticum or pathogenic bacteria were isolated more frequently from villous tissue of placentas from cases with chorioamnionitis (p less than 0.01) but not Mycoplasma hominis, Chlamydia trachomatis, or viruses. Furthermore, there was a higher prevalence of both elevated fetal antibody titer to U. urealyticum (p less than 0.025) and fetal titer fourfold above maternal titers (p less than 0.05) in cases with chorioamnionitis. The antibody responses and presence of microorganisms suggest that chorioamnionitis is associated with intrauterine infection and an associated increase in perinatal morbidity and mortality.