O10.2 The Netherlands Chlamydia Cohort Study: Adverse pregnancy outcomes in women with and without a previous chlamydia infection

Background Chlamydia trachomatis infections can cause reproductive tract problems, but it remains unclear to what extent past infections are associated with reproductive outcomes such as miscarriages, preterm birth and stillbirth. We assessed these outcomes in women with and without a previous chlamydia infection in women participating in the Netherlands Chlamydia Cohort Study (NECCST). Methods NECCST is a cohort of 5,704 women of reproductive age all tested for chlamydia by PCR in a chlamydia screening study between 2008–11. Women were re-invited for NECCST in 2015–16. Chlamydia-status (positive/negative) was defined using results from the screening, CT IgG presence in serum and/or self-reported past chlamydia infections. Data on miscarriages (spontaneous abortion 15 weeks of pregnancy), was collected via questionnaires in 2019–20. Pregnancy outcomes were compared between chlamydia positive and chlamydia negative women using multivariable logistic regression analyses. Results Of 3,517 (61.7%) women enrolled in the third NECCST round, 1,011 (28.8%) were chlamydia positive and 2,052 (58.3%) had been pregnant at least once. In preliminary results of those 2,052 women, 585 (28.5%) had a miscarriage once, 153 (7.5%) had a preterm birth and 18 (0.9%) a stillbirth. Miscarriages and stillbirths were similar among chlamydia positive and negative women, 30.7% versus 28.3% p=0.280 and 1.1% versus 0.8% p=0.590. Preterm births were more common among chlamydia positive women compared to chlamydia negatives, 9.7% versus 6.6%, p=0.017. However, in multivariable analysis corrected for age, education level, migration background, body mass index and smoking, the odds of a preterm birth were not significantly higher for chlamydia positive versus chlamydia negative women, OR 1.37 (95%CI 0.95–1.96). Conclusion In the NECCST study we found no indication that past Chlamydia trachomatis infections are associated with an increased risk for miscarriages, preterm births or stillbirths.