Abstract
This study aims to investigate the association between exposure to toxic indoor chemicals, specifically polyhexamethylene guanidine (PHMG) and oligo(2-(2-ethoxy) ethoxyethyl guanidinium) chloride (PGH), used in humidifier disinfectants, and gestational diabetes mellitus (GDM). We confirmed pregnancy from 2003 to 2017 and identified GDM by linking a cohort of claimants who reported exposure to PHMG/PGH with National Health Insurance Service data. The GDM incidence was calculated, and PHMG/PGH exposure characteristics-exposure status, the humidifier's distance/location, and exposure duration/hours-were investigated. Logistic regression and mediation analysis were applied using asthma, frequently treated with steroids, as a mediator. Among 521 pregnancies, 38 were identified as GDM, with 2.4% before exposure and 8.9% after exposure. Pregnancies after exposure had a higher odds ratio (OR) for GDM (OR 2.968, 95% CI: 1.004-12.725). A trend of increased GDM risk was observed with longer exposure duration/hours. Additionally, pregnancies after exposure demonstrated total and direct effects on GDM (β = 0.0435, p = 0.036, β = 0.0432, p = 0.030) independent of the indirect effects by asthma. The incidence of GDM was higher after PHMG/PGH exposure compared to before. PHMG/PGH exposure was associated with GDM, independent of asthma. Further research is warranted to confirm these findings in exposed cohorts and to explore the underlying mechanisms.