Adverse Pregnancy Outcomes and Coxiella burnetii Antibodies in Pregnant Women, Denmark

A high risk for obstetric complications has been reported among women infected with Coxiella burnetii, the causative agent of Q fever, but recent studies have failed to confirm these findings. We reviewed national data collected in Denmark during 2007-2011 and found 19 pregnancies in 12 women during which the mother had a positive or equivocal test for antibodies to C. burnetii (IgM phase I and II titers >= 64, IgG phase I and II titers >= 128). Of these 12 women, 4 experienced obstetric complications (miscarriage, preterm delivery, infant small for gestational age, oligohydramnion, fetal growth restriction, or perinatal death); these complications occurred in 9 pregnancies (47% of the 19 total pregnancies identified). Our findings suggest an association between Q fever and adverse pregnancy outcomes, but complications were identified in only 9 pregnancies during the study's 5-year period, indicating that the overall risk is low.