In-utero exposure to multiple air pollutants and childhood undernutrition in India

Abstract

Background: Several studies have been conducted to understand the impact of socioeconomic and maternal factors on child undernutrition. However, the past literature has not directly examined the joint impacts of fuel use and ambient pollution and have primarily focused on PM_2.5.

Objective: This study explored the individual and community-level associations of both indoor (cooking fuel type) and ambient air pollution (PM_2.5, NO₂ and SO₂) during maternal gestation on child undernutrition.

Methods: This study analysed stunting, being underweight, and anaemia of children aged 0-59 months (n = 259,627) using the National Family Health Survey. In-utero exposures to ambient PM_2.5, NO_2, and SO₂ were measured using satellite data and self-reported fuel type was a marker of indoor pollution exposure. The study used univariate and bivariate Moran's I, spatial lag model and multivariable logistic regression models after adjusting for other covariates to understand the effect of pollution on in-utero exposure and child health status at the individual and community-levels.

Results: Higher concentration of indoor and ambient air pollution was found in the Northern and parts of Central regions of India. Estimates of spatial modelling show that each 1 μg/m^-3 increase in maternal exposure to ambient PM_2.5 across the clusters of India was associated with a 0.11, 9 and 19 percentage points increase in the prevalence of stunting, underweight and anaemia, respectively. The results of multi-pollutant model show that a higher ambient PM_2.5 exposure during pregnancy was linked to higher odds of stunting (AOR:1.38; 95% CI:1.32-1.44), underweight (AOR:1.59; 95% CI:1.51-1.67) and anaemia (AOR:1.61; 95% CI:1.52-1.69) in children. Weaker but similar associations were observed for NO₂, but not with SO₂. Indoor pollution exposure during in-utero periods was also significantly associated with childhood undernutrition and this association was modified by ambient PM_2.5 levels, where exposure to both indoor and ambient air pollution had even greater odds of being undernourished.

Impact statement: Our research on multi-pollutant models has revealed the initial proof of the individual impacts of indoor and outdoor pollution (PM_2.5, NO₂, and SO₂) exposure during fetal development on children's nutrition.

Keywords: Ambient air pollution; In-utero exposure; India; Indoor air pollution; Multipollutants; Undernutrition.