Coxiella burnetii seropositivity in parturient women is associated with adverse pregnancy outcomes.

Abstract

We conducted a cohort study of parturient women in an area with endemic Q fever infection to determine whether those seropositive for Coxiella burnetii had evidence of adverse birth outcomes. From June 1997 to November 1998, the cord blood of all women delivered at our health center was tested for antibodies to C burnetii by indirect immunofluorescence antibody test by using purified whole cell strain Nine Mile antigens. A titer of 1:8 or greater to either phase I or phase II antigens was considered seropositive. Placentas of a sample of cases and seronegative controls had polymerase chain reaction and culture performed. Evidence of prior infection with C burnetii was found in 3.8% (291/7658) of all parturient women. In a multivariate logistic regression, an association was seen between seropositivity (phase I titer >or= 1:8 or phase II titer >or= 1:32) and newborn gestational age >or=36 weeks (phase I antibody, odds ratio [OR] 2.4, 95% CI 1.3-4.3, P =.005; phase II antibody, OR 1.9, 95% CI 1.02-3.7, P =.04). Women with phase I antibody were more likely to have a prior or current neonatal death (phase I OR 3.2, 95% CI 1.09-9.3, P =.03). No placental samples from 153 seropositive or 93 seronegative women had Q fever by polymerase chain reaction or culture. About 4% of parturient women in this endemic area have evidence of previous exposure to C burnetii and this exposure is associated with adverse pregnancy outcomes. The pathogenesis of this association remains to be determined.