Exposure to night-time light pollution and risk of prolonged duration of labor: A nationwide cohort study.

BACKGROUND Light pollution (LP) is a ubiquitous environmental agent that affects more than 80% of the world's population. This large nationwide cohort study evaluates whether exposure to LP can influence obstetric outcomes. METHODS We analyzed Austrian birth registry data on 717 113 cases between 2008 and 2016 and excluded cases involving day-time delivery, <23 + 0 gestational weeks, and/or birthweight <500 g, induction of labor, elective cesarean, or cases with missing data. The independent variable, that is, degree of night-time LP, was categorized as low (0.174 to <0.688 mcd/m2 ), medium (0.688 to <3 mcd/m2 ), or high (3 to <10 mcd/m2 ). Duration of labor and adverse neonatal outcomes served as outcome measures. RESULTS Cases in regions with high LP (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.30-1.57) and medium LP (OR, 1.22; 95% CI, 1.14-1.31) showed increased odds of prolonged labor (P < .0001 each). Newborns born in regions with high LP (OR, 1.12; 95% CI, 1.07-1.16) and medium LP (OR, 1.07; 95% CI, 1.04-1.10) showed increased odds of experiencing adverse outcomes (P < .0001 each). Preterm delivery <28 + 0 weeks was also associated with the degree of LP (P = .04). CONCLUSIONS Night-time LP negatively interferes with obstetric outcomes. The perceived influence of LP as an environmental agent needs to be re-evaluated to minimize associated health risks.