Maternal exposure to PM_2.5 and its association with adverse pregnancy and birth outcomes: A prospective cohort study

Maternal exposure to ambient air pollution is linked to various adverse pregnancy and birth outcomes (AP&BO). However, the association between particulate matter with a diameter of 2.5 μm (PM_2.5) and AP&BO in India remains largely unexplored.

We aimed to investigate the association between PM_2.5 exposure and adverse pregnancy and birth outcomes in a prospective, hospital-based cohort study.

406 pregnant women aged 19-35, who were in their third trimester, were enrolled as per the inclusion/exclusion criteria. The study participants were divided into two groups according to their residential area's air quality: Unexposed (203) and Exposed (203). A questionnaire was filled and 5 mL of umbilical cord blood and placental tissues were collected after delivery. Additionally, we analysed the systemic inflammatory markers (CRP, IL-6, TNF-α, and IL-1β) in the cord blood and the presence of black carbon in 50 placental tissue samples.

Each 10 µg/m³ increase in PM_2.5 had a statistically significant relation with pre-eclampsia, preterm labor, preterm birth, low birth weight, and small for gestational age, even after accounting for possible confounders. A statistically significant association between CRP, IL-6, TNF-α, and IL-1β, with each 10 µg/m³ increase of PM_2.5, was observed. Black carbon (BC) deposition was detected at the foetal side of the placenta only in the exposed group.

Our study indicates that maternal exposure to increased levels of PM_2.5 during the third trimester is associated with an increased risk for AP&BO.