Gestational exposure to PM 2.5 , NO 2 , and sex steroid hormones: Identifying critical windows of exposure in the Rochester UPSIDE Cohort.

Background: Sex steroid hormones are critical for maintaining pregnancy and optimal fetal development. Air pollutants are potential endocrine disruptors that may disturb sex steroidogenesis during pregnancy, potentially leading to adverse health outcomes.
Methods: In the Environmental influences on Child Health Outcomes Understanding Pregnancy Signals and Infant Development pregnancy cohort (Rochester, NY), sex steroid concentrations were collected at study visits in early-, mid-, and late-pregnancy in 299 participants. Since these visits varied by the gestational age at blood draw, values were imputed at 14, 22, and 30 weeks gestation. Daily NO ₂ and PM _2.5 concentrations were estimated using random forest models, with daily concentrations from each 1-km ² grid containing the subject's residence. Associations between gestational week mean NO ₂ and PM _2.5 concentrations and sex steroid concentrations were examined utilizing distributed lag nonlinear models.
Results: Each interquartile range (IQR = 9 ppb) increase in NO ₂ during weeks 0-5 was associated with higher early-pregnancy total testosterone levels (cumulative β = 0.45 ln[ng/dl]; 95% CI = 0.07, 0.83), while each IQR increase in NO ₂ during weeks 12-14 was associated with lower early-pregnancy total testosterone levels (cumulative β = -0.27 ln[ng/dl]; 95% CI = -0.53, -0.01). Similar NO ₂ increases during gestational weeks 0-14 were associated with higher late-pregnancy estradiol concentrations (cumulative β = 0.29 ln[pg/ml]; 95% CI = 0.10, 0.49), while each IQR increase in NO ₂ concentrations during gestational weeks 22-30 was associated with lower late-pregnancy estradiol concentrations (cumulative β = -0.18 ln[pg/ml]; 95% CI = -0.34, -0.02). No associations with PM _2.5 were observed, except for an IQR increase in PM _2.5 concentrations (IQR = 4 µg/m ³ ) during gestational weeks 5-11 which was associated with lower late-pregnancy estriol levels (cumulative β = -0.16 ln[ng/ml]; 95% CI = -0.31, -0.00).
Conclusions: Residential NO ₂ exposure was associated with altered sex steroid hormone concentrations during pregnancy with some indication of potential compensatory mechanisms.
Competing Interests: The authors declare that they have no conflicts of interest with regard to the content of this report.
(Copyright © 2025 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The Environmental Epidemiology. All rights reserved.)