Chlamydia trachomatis infection during pregnancy and the risk of preterm birth: a case-control study.

Our goal was to define the risks of preterm birth associated with Chlamydia trachomatis (CT) and other sexually transmitted infections (STIs) among pregnant women. We accessed clinical records from July 2005 to February 2008. The study population included all pregnant women who gave birth to a singleton newborn of at least 20 weeks' gestation, and who had antenatal care information. We estimated the impact of CT and other STI on the odds of preterm birth using logistic regression. Overall, 2127 women were included in this analysis. The prevalence of CT infection was 4.7%. CT diagnosis was not associated with preterm birth. In conclusion, this study did not find an association between CT and preterm birth. The lack of an association may be explained by early treatment. Future studies evaluating the timing of screening for STIs may help clarify whether pregnant women would benefit more from earlier screening.