Exposures to fine particulate matter (PM) and birthweight in a rural-urban, mother-child cohort in Tamil Nadu, India.

Background: Exposure to PM (fine particulate matter
Objectives: We examined whether PM exposures during pregnancy were associated with birthweight in an integrated rural-urban, mother-child cohort in the state of Tamil Nadu, India.

Methods: We recruited 1285 pregnant women in the first trimester of pregnancy from primary health care centers and urban health posts and followed them until birth to collect antenatal care data and birthweight. We estimated pregnancy period PM exposures through direct serial measurements of 24-h household PM concentrations, performed across each trimester. Mothers also completed detailed questionnaires to provide data on covariates related to household, socio-economic, demographic and maternal health characteristics. The association between PM exposures and birth weight was assessed using linear and logistic regression models that controlled for potential confounders.

Results: A 10-μg/m increase in pregnancy period PM exposures was associated with a 4g (95% CI: 1.08g, 6.76g) decrease in birthweight and 2% increase in prevalence of low birthweight [odds ratio(OR) = 1.02; 95%CI:1.005,1.041] after adjusting for gestational age, infant sex, maternal BMI, maternal age, history of a previous low birth weight child, birth order and season of conception.

Conclusions: The study provides some of the first quantitative effects estimates for linking rural-urban PM exposures and birthweight in India, adding important evidence for this association from high exposure settings in LMICs, that also experience dual health burdens from ambient and household air pollution. Study results also point to the need for considering maternal PM exposures alongside other risk factors for low birthweight in India.