Chlamydia trachomatis infection may increase the risk of preeclampsia

Background: Although the etiology of preeclampsia is not well understood, it has been suggested that excessive systemic inflammation may lead to oxidative stress, promoting the endothelial dysfunction characteristic of preeclampsia. Few prospective studies have examined the role of infection, an immune system stimulator, as a risk factor for preeclampsia.

Methods: We conducted a longitudinal study of the relationships between Chlamydia trachomatis (CT), Chlamydophila pneumoniae (CP), cytomegalovirus (CMV), herpes simplex virus (HSV) and preeclampsia among 509 preeclamptic cases and 336 normotensive controls nested within the Danish National Birth Cohort study. Antibodies were analyzed at a first prenatal visit (mean 17.0weeks) and at a late second/third trimester study visit. Prenatal infections were identified as IgG/IgM seroconversion or a fourfold rise in IgG antibody titers. Multiple regression models were adjusted for maternal age, BMI, smoking status, and time between blood draws.

Results: CT infection was associated with preeclampsia (ORadj 1.6, 95% CI 0.7, 3.6), severe preeclampsia (ORadj 1.8, 95% CI 0.6, 5.3), and preeclampsia resulting in preterm birth (ORadj 1.7, 95% CI 0.6-4.9) or birth of a small for gestational age infant (ORadj 2.1, 95% CI 0.6, 7.5), although CT infection was uncommon (n=33, 4.0%) and associations were not statistically significant. CP, CMV, and HSV infection were not associated with preeclampsia.

Conclusions: Women with serological evidence of prenatal CT infection were more likely to develop preeclampsia, although infection was infrequent and confidence intervals were wide. Studies in populations at higher risk for STIs are needed to corroborate this association.