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

Objective: 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.

Study Design: 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.

Results: 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.

Conclusion: 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.