Prenatal Chlamydia Exposure and Early Neonatal Respiratory Failure in Very Preterm Infants

Purpose: To investigate the association between prenatal Chlamydia exposure and early neonatal respiratory failure in very preterm infants (VPIs). Methods: This population-based cohort study utilized birth data submitted by 50 states and the District of Columbia to the National Vital Statistics System database in the USA. The study included all VPIs with a gestational age of 24 to 31 weeks from January 1, 2021, to December 31, 2022. Infants exposed to Chlamydia were compared with unexposed infants (No Chlamydia exposure) selected through propensity score matching at a 1:2 ratio, adjusting for confounding factors. The primary outcome was neonatal respiratory failure, defined as the requirement for assisted ventilation for more than six hours, as recorded in the database. Results: After propensity score matching, 2,757 Chlamydia-exposed infants and 5,507 No Chlamydia-exposure infants were compared. Infants with Chlamydia exposure had a significantly higher relative risk of neonatal respiratory failure compared to No Chlamydia-exposure infants (30.5%, 840/2757 vs. 25.4%, 1401/5507; risk ratio [RR] 1.20 [95% CI, 1.13-1.29]). Additionally, the risk of assisted ventilation required immediately following delivery was higher in the Chlamydia-exposed group (47.2%, 1300/2757 vs. 41.5%, 2283/5507; RR 1.15 [95% CI, 1.10-1.20]). Subgroup analyses by gestational age, sex, and other factors demonstrated consistent results for the primary outcome. Sensitivity analyses, including total infants, 1:1 propensity score matching, and 1:3 propensity score matching, yielded similar findings. Conclusion: Prenatal Chlamydia exposure significantly associated with an increased risk of neonatal respiratory failure in VPIs. Further investigation is warranted to develop intervention strategies aimed at preventing neonatal respiratory failure in high-risk infants with prenatal Chlamydia exposure.

Publication History

Received: 16 June 2025

Accepted after revision: 11 August 2025

Accepted Manuscript online:
12 August 2025