Chlamydia trachomatis, a prevalent bacterial sexually transmitted infection, is known to increase the risk of reproductive complications such as pelvic inflammatory disease (PID), tubal infertility, and ectopic pregnancy. Despite the widespread testing efforts to mitigate these risks, particularly for asymptomatic cases, achieving a significant population-level impact has been challenging.
Previous studies have shown a heightened risk of reproductive complications following chlamydia infection, but issues such as data misclassification and inconsistent diagnostic methods have impacted their reliability. This study aims to provide a clearer understanding by assessing the long-term reproductive risks associated with symptomatic and asymptomatic chlamydia infections.
Study Design and Methods
This prospective cohort study involved 5,704 women of reproductive age, with a mean age of 35.3 years, from the Netherlands Chlamydia Cohort Study. Participants, recruited from a prior screening study, were followed from 2008 to 2022. Data were collected via questionnaires and linked with previous screening records to evaluate chlamydia infections and reproductive outcomes.
Exposure to chlamydia was determined through PCR tests, self-reported infections, and serological assays. The study compared outcomes of PID, ectopic pregnancy, and tubal factor infertility between chlamydia-positive and chlamydia-negative women. Statistical analyses included various tests and models to account for confounding factors and to assess risks accurately.
Findings
Of the participants, 36.2% completed all study rounds, with a mean age at sexual debut of 16.9 years and an average exposure duration of 18.3 years. Chlamydia-positive women showed higher body mass index, earlier sexual debut, more lifetime sexual partners, and increased gonorrhea positivity compared to chlamydia-negative women.
Among participants, 4.1% experienced PID, 1.6% reported ectopic pregnancy, and 1% had tubal factor infertility. Chlamydia-positive women had a significantly higher rate of PID (3.80 per 1,000 person-years) compared to chlamydia-negative women (1.80 per 1,000 person-years), with symptomatic infections showing an even higher incidence (5.82 per 1,000 person-years).
Multivariable analyses indicated that chlamydia positivity was linked to increased risks of PID (adjusted hazard ratio [aHR] 1.62), ectopic pregnancy (aHR 1.84), and tubal factor infertility (aHR 2.75). Symptomatic infections were associated with a greater risk of these complications, while asymptomatic infections did not show the same level of risk.
Pregnancy rates were higher among chlamydia-positive women (67.2 per 1,000 person-years) compared to chlamydia-negative women (41.9 per 1,000 person-years) during the first exposure interval. However, chlamydia-positive women, particularly in younger age groups, had lower chances of planned pregnancies, with no significant difference observed in older age groups. The time required to conceive was longer for women with a history of chlamydia.
Conclusion
This large-scale, long-term study underscores that symptomatic chlamydia infections significantly increase the risk of reproductive complications such as PID, ectopic pregnancy, and tubal factor infertility. While the incidence of these complications was relatively low, the findings highlight the need for primary prevention, early detection, and timely treatment of chlamydia, particularly for young women.
Future public health strategies should include tailored screening programs that address disparities in social and healthcare access to improve reproductive health outcomes for women of reproductive age.
