A cohort study published in "BMC Medicine" depicted that the changes in growth rate and ultimate weight from the third trimester to the age of two years were associated with prenatal exposure to outdoor air pollution. Nan Ji et al. conducted this study with the objective of assessing how prenatal exposure to outdoor air pollutants is linked to changes in weight patterns from the third trimester of pregnancy until a child reaches two years of age.

In total, the study encompassed a group of 490 expectant mothers who were drawn from the Maternal and Development Risks from Environmental and Social Stressors (MADRES) cohort. This cohort primarily consisted of low-income, predominantly Hispanic individuals residing in Los Angeles, California. Estimation of the exposure to environmental factors like nitrogen dioxide (NO2), particulate matter lower than 10 micrometers (PM10), particulate matter lower than 2.5 micrometers (PM2.5), and ozone (O3) was carried out during the pregnancy period by utilizing data from official air quality monitoring stations.

Fetal weight was determined using data from maternal ultrasound records, while measurements of infant and child weight were either collected from medical records or obtained during subsequent check-up visits. To analyze the impact of air pollutants on growth during specific timeframes, overall growth, and weight, the researchers employed piecewise spline models. The mean (standard deviation [SD]) prenatal exposure levels were as follows: 16.4 (2.9) parts per billion (ppb) for NO2, 12.0 (1.1) micrograms per cubic meter (μg/m3) for PM2.5, 28.5 (4.7) μg/m3 for PM10, and 26.2 (2.9) ppb for O3.

When comparing an elevation in average prenatal air pollutant levels from the 10th percentile to the 90th percentile, several notable effects were observed. Specifically, there was a substantial elevation in the growth rate from the third trimester to age 3 months (1.55% for PM2.5 and 1.64% for NO2). Conversely, there was a significant decline in the growth rate from 6 months to 2 years of age (0.90% for NO2). Additionally, the attained weight at age 2 years was substantially reduced (-7.50% for PM10 and -7.00% for NO2).

The fluctuations in growth rate and final weight from the third trimester to the age of two years were linked to prenatal exposure to outdoor air pollution. These findings underscore the ongoing importance of decreasing ambient air pollution levels, particularly within underserved communities, for the sake of public health.