ABSTRACT Background Chlamydia trachomatis (CT) diagnoses are highest among females of reproductive age. Yet, little is known about adverse infant outcomes associated with treatment for CT infections during pregnancy, including birth defects. Methods Using de‐identified matched data from the New York State (NYS) Sexually Transmitted Infection Surveillance Registry and live births reported to the NYS Birth Defects Registry from 2010 to 2020, we conducted a retrospective cohort study among pregnancies with one first‐trimester CT diagnosis to assess the impact of adequate CT treatment on the risk of selected birth defects. Results Pregnancies with evidence of adequate CT treatment during the first trimester were more likely (adjusted risk ratio ARR: 3.0, 95% confidence interval CI: 1.7–5.2) to have an infant with at least one selected birth defect. This association was attenuated in sensitivity analyses including pregnancies with evidence of adequate treatment any time during pregnancy (ARR: 1.2, 95% CI: 0.7–2.1) and evidence of adequate treatment through the second trimester (ARR: 1.9, 95% CI: 0.8–4.9). Conclusion Results did not support the hypothesis that adequate first‐trimester CT treatment was associated with a decreased risk of selected birth defects. However, additional investigation is warranted to understand if an association is driven by the timing of infection or treatment.
Boos et al. (2026) studied this question.