Robust relationship between ambient air pollution and infant mortality in India.

Background: Ambient exposure to fine particulate matter (PM) is one of the top global health concerns. We estimate the associations between in-utero and perinatal exposure to PM and infant, neonatal and postneonatal mortality in India. We evaluate the sensitivity of this association to two widely-used exposure assessments.

Method: We linked nationally representative anthropometric data from India's 2015-2016 Demographic and Health Survey (n = 259,627 children under five across 640 districts of India) with satellite-based PM concentrations during the month of birth of each child. We then estimated the associations between PM from each dataset and child mortality, after controlling for child, mother and household factors including trends in time and seasonality. We examined if factors: urban/rural, sex, wealth quintile and state modified the associations derived from the two datasets using Wald tests.

Results: We found evidence that PM impacts infant mortality primarily through neonatal mortality. The estimated association between neonatal mortality and PM in trimester 3 was OR: 1.016 (95% CI: 1.003, 1.030) for every 10 μg/m increase in exposure. This association was robust to the exposure assessment used. Child sex was a significant effect modifier, with PM impacting mortality in infant girls more than boys.

Conclusions: Our results revealed a robust association between ambient exposure to PM in the latter period of pregnancy and early life with infant and neonatal mortality in India. Urgent air pollution management plans are needed to improve infant mortality in India.