BACKGROUND: A Chlamydia trachomatis infection (chlamydia) can result in tubal factor infertility in women. To assess if this association results in fewer pregnant women, we aimed to assess pregnancy incidences and time to pregnancy among women with a previous chlamydia infection compared to women without one and who were participating in the Netherlands Chlamydia Cohort Study (NECCST).
METHODS: NECCST is a cohort of women of reproductive age tested for chlamydia in a chlamydia screening trial (CSI) between 2008-2011 and re-invited for NECCST in 2015-2016. Chlamydia status (positive/negative) was defined using CSI-NAAT results, chlamydia IgG presence in serum or self-reported chlamydia infections. Data on pregnancies was collected via questionnaires in 2015-2016 and 2017-2018. Overall pregnancies (i.e. planned and unplanned) and time to pregnancy (among women with a pregnancy intention) were compared between chlamydia-positive and chlamydia-negative women using Cox regressions.
RESULTS: Of 5,704 women enrolled, 1717 (30.1%, 95%CI 28.9-31.3) women was chlamydia positive. Overall pregnancy proportions were similar in chlamydia-positive and -negative women (49.0%, 95%CI 46.5-51.4 versus 50.5%, 95%CI 48.9-52.0). Pregnancies per 1000 person-years was 53.2 (95%CI 51.5-55.0) for chlamydia negatives and 83.0 (95%CI 78.5-87.9) for chlamydia positives. Among women with a pregnancy intention, 12% of chlamydia-positive women had a time to pregnancy of >12 months compared to 8% of chlamydia negatives, p<0.01.
CONCLUSIONS: Overall pregnancy rates were not lower in chlamydia-positive women compared to chlamydia-negative women, but among women with a pregnancy intention time to pregnancy was longer and pregnancy rates were lower in chlamydia-positive women.Dutch Trial Register NTR-5597.