Artificial Light at Night and Hypertensive Disorders of Pregnancy: Socioeconomic Inequality in the China Birth Cohort Study

Abstract Evidence regarding the association of outdoor artificial light at night (ALAN) with hypertensive disorders of pregnancy (HDPs) remains limited. Between February 2018 and December 2022, 241,608 participants from the China Birth Cohort Study (CBCS), which enrolled individuals from 17 provinces across China, were included in the analysis. HDP was defined by physician clinical diagnosis. We estimated outdoor ALAN within 500 m, sourced from the VIIRS/DNB, using the address of each participant, and categorized it into quartiles (lowest [Q1] as reference). We used generalized linear mixed models (GLMMs) to assess the association between ALAN exposure and HDPs. Effect modification by province-level per capita gross domestic product (GDP), household income, and other factors was also explored. A total of 9383 (3.88%) participants were diagnosed with HDPs. After adjusting for covariates, compared with Q1, the odds ratios (ORs) for HDPs were 1.14 (95% CI: 1.07–1.21) for quartile 2 (Q2), 1.21 (95% CI: 1.13–1.29) for quartile 3 (Q3), and 1.09 (95% CI: 1.02–1.17) for quartile 4 (Q4). Furthermore, province-level per capita GDP and household income modified the associations between the ALAN and HDPs. Compared to participants residing in low-GDP areas with low income, the strongest effect estimate was observed among participants residing in high-GDP areas with low income (OR: 1.15 [1.09–1.20] vs 0.97 [0.91–1.04] for HDPs).