In a recent prospective cohort study published in The Lancet Regional Health – Europe, researchers from the Netherlands investigated the risks of reproductive complications after asymptomatic and symptomatic infections with Chlamydia trachomatis (chlamydia).
They found that only symptomatic chlamydia infections significantly increased the risk of pelvic inflammatory disease (PID), ectopic pregnancy, and tubal factor infertility, although the incidence of these complications remained low.
Study: Reproductive tract complication risks following Chlamydia trachomatis infections: a long-term prospective cohort study from 2008 to 2022. Image Credit: New Africa/Shutterstock.com
Background
Chlamydia trachomatis is the most common bacterial sexually transmitted infection globally. Its widespread testing aims at reducing complications like PID, which may lead to tubal infertility and ectopic pregnancy. While individual-level screening reduces PID risk, achieving population-level impact has been challenging, especially for asymptomatic cases, which are common.
Previous randomized controlled trials have indicated increased risks for reproductive complications post-chlamydia infection, but data misclassification and inconsistent diagnostic methods have limited their accuracy.
Prospective studies with updated chlamydia status and comprehensive fertility outcomes could offer a more accurate assessment of chlamydia's impact on female fertility.
Therefore, researchers in the present study assessed the long-term risks of chlamydia-associated complications (PID, tubal factor infertility, and ectopic pregnancy) and their impact on pregnancy, comparing outcomes for asymptomatic and symptomatic infections to potentially guide chlamydia policy and treatment.
About the study
This study involved a long-term prospective cohort of 5704 reproductive-age women, of mean age 35.3 years, from the Netherlands Chlamydia Cohort Study. About 64.7% of the participants had been pregnant at least once. They were recruited from a prior chlamydia screening study and were followed from 2008 to 2022.
Data on chlamydia infections, pregnancies, and reproductive complications were collected through questionnaires and merged with previous screening data.
Chlamydia exposure was classified based on polymerase chain reaction (PCR) test results, self-reported infections, and serological tests for the presence of chlamydia antibodies.
The study aimed to assess risks of PID, ectopic pregnancy, tubal factor infertility, and time to pregnancy in chlamydia-positive (n = 2103) vs. chlamydia-negative women (n = 3691) over time.
Statistical analysis involved the use of Student's t-test, Mann–Whitney U-test, chi-square tests, Kaplan–Meier curves, Cox proportional hazards regression model, and confounder assessment, followed by stratified and sensitivity analysis.
Results and discussion
Of the total participants, 36.2% completed all four study rounds, while others contributed to fewer rounds. The mean age at sexual debut was found to be 16.9 years, with an average exposure time of 18.3 years.
Chlamydia-positive women were found to have a higher body mass index, a younger age at sexual debut, more lifetime sexual partners, and increased gonorrhea positivity compared to chlamydia-negative women.
About 4.1% of the participants had at least one episode of PID, 1.6% of them reported at least one ectopic pregnancy, and 1% of them were diagnosed with tubal factor infertility.
Chlamydia-positive women were found to have significantly higher rates of PID at 3.80 per 1000 person-years, compared to 1.80 per 1,000 person-years in chlamydia-negative women. For symptomatic chlamydia, the incidence was even higher at 5.82 per 1000 person-years.
Multivariable analyses showed that chlamydia-positivity was associated with increased risks of PID (adjusted hazard ratio [aHR] 1.62), ectopic pregnancy (aHR 1.84), and tubal factor infertility (aHR 2.75).
Interestingly, while symptomatic chlamydia infections were linked to a higher risk of adverse reproductive outcomes, asymptomatic infections were not found to show the same association.
Pregnancy rates were found to be higher among chlamydia-positive women (67.2 per 1000 person-years) compared to chlamydia-negatives (41.9 per 1000 person-years) during the first exposure interval. However, there were lower chances of planned pregnancies among chlamydia-positive women in the younger age groups (16–25 years and 26–33 years).
No significant difference was observed in the older age groups (34–42 years). While overall pregnancy chances were not decreased after chlamydia infection, the duration required to conceive was longer for those with a history of chlamydia.
This is the first prospective study to provide a long-term, large-scale, cohort-based analysis of chlamydia's reproductive risks. However, the study is limited by its potential misclassification of lifetime chlamydia status, reliance on self-reported outcomes, possible diagnostic and selection biases, and unmeasured residual confounding.
Conclusion
In conclusion, the study reveals the long-term reproductive health risks associated with chlamydia infections, highlighting that symptomatic chlamydia infections pose a greater risk for complications like PID, ectopic pregnancy, and tubal factor infertility.
Despite the low incidence of reproductive risks found in the study, the researchers emphasize the importance of primary prevention, early detection, and timely treatment of chlamydia, especially in young women.
In the future, tailored screening and public health strategies for chlamydia would be required, that also consider social and healthcare access disparities to improve health outcomes in women of reproductive age.
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