Preconception Chlamydia trachomatis seropositivity and fecundability, live birth, and adverse pregnancy outcomes

To study the impact of preconception Chlamydia trachomatis seropositivity on fecundability, live birth, and pregnancy loss and to assess the effect of low-dose aspirin therapy (81 mg/day) on live birth and pregnancy loss.

Preconception cohort study conducted using data and specimens from the Effects of Aspirin in Gestation and Reproduction study-a randomized placebo-controlled trial.

A total of 1,228 individuals with proven fecundity and a history of 1-2 pregnancy losses.

Preconception C. trachomatis seropositivity determined using an enzyme-linked immunoabsorbent assay-based synthetic peptide assay at baseline.

Time-to pregnancy (fecundability) was defined as number of menstrual cycles to beta human chorionic gonadrotropin-detected pregnancy; live birth status was determined from medical record abstraction; pregnancy loss was defined as any loss post positive beta human chorionic gonadrotropin test.

After adjusting for confounders (baseline demographic and reproductive history variables), C. trachomatis seropositivity (n = 134/1228, 11%) was associated with a reduced live birth likelihood (relative risk [RR]: 0.77, 95% confidence interval [CI]: 0.59, 0.99) and an increased risk of pregnancy loss (RR: 1.16, 95% CI: 1.04, 1.29), but was not associated with fecundability (fecundability odds ratio: 0.92, 95% CI: 0.71, 1.20). Among a subset of C. trachomatis seropositive individuals with chronic inflammation indicated by increased C-reactive protein levels ≥1.95 but ≤10 mg/L (n = 50/134, 37.3%), low-dose aspirin therapy improved live birth rates (RR: 1.68, 95% CI: 0.96, 2.92) and reduced the risk of pregnancy loss (RR: 0.83, 95% CI: 0.65, 1.10). However, the sample size reduced precision.

Prior exposure to C. trachomatis among women with a history of pregnancy loss may impact risk of pregnancy loss. Our results indicate the need for future studies exploring mechanisms by which C. trachomatis may influence long-term reproductive function, because this may identify treatments to improve outcomes among those with a history of infection.