Linking weather and health outcomes: Examining the potential influences of weather factors and particulate matter pollution on adverse pregnancy outcomes in the Kavre district, Nepal

Introduction: Adverse pregnancy outcomes (APOs) include stillbirth, preterm birth, and low birthweight (LBW). Studies exploring the impact of weather factors and air pollution on APOs are scarce in Nepal. We examined the impacts of prenatal exposure to temperature, precipitation, and air pollution (PM_2.5) on APOs among women living in Kavre, Nepal. Methods: We conducted a hospital and rural health centers-based historical cohort study that included health facility birth records (n = 1716) from the Nepali fiscal year 2017/18 through 2019/20. We linked health records to temperature, precipitation, and PM_2.5 data for Kavre for the six months preceding each birth. A random intercept model was used to analyze birthweight, while a composite APO variable, was analyzed using multivariable logistic regression in relation to environmental exposures. Results: The proportion of LBW (<2500 gm), preterm birth (babies born alive before 37 weeks of gestation), and stillbirth was 13%, 4.3%, and 1.5%, respectively, in this study. Overall, around 16% of the study participants had one or more APOs. Total precipitation (β: 0.17, 95% CI 0.01 to 0.33, p = 0.03) had a positive effect on birthweight in the wetter season. Negative effects for mean maximum (β: 33.37, 95% CI -56.68 to −10.06, p = 0.005), mean (β: 32.35, 95% CI -54.44 to −10.27, p = 0.004), and mean minimum temperature (β: 29.28, 95% CI -49.58 to −8.98, p = 0.005) on birthweight was also observed in the wetter season. Conclusion: A positive effect of temperature (mean maximum, mean, and mean minimum) and total precipitation on birthweight was found in the wetter season. This study emphasizes the need for future research using larger cohorts to elucidate these complex relationships in Nepal.