Prenatal PM2.5 and carbon monoxide exposure linked to higher odds of low birth weight in Fujian cohort

A retrospective cohort study of 41,397 mother-infant pairs recorded at the Obstetrics Department of Fujian Provincial Maternal and Child Health Hospital from 2015 to 2019 found that exposure to fine particulate matter (PM2.5) and carbon monoxide (CO) during the full trimester was associated with increased odds of low birth weight. The cohort included 1,532 newborns classified as having low birth weight. Logistic regression estimates were an odds ratio of 1.022 for full-trimester PM2.5 exposure (95% confidence interval, 1.002–1.042) and 1.014 for full-trimester CO exposure (95% confidence interval, 1.001–1.027). The supplied abstract does not identify the exposure increment used for these odds ratios.

Researchers used logistic regression to examine associations between individual exposures to air pollutants and low birth weight during different gestational periods. They combined the analysis with a distributed lag nonlinear model to explore exposure timing and possible vulnerable windows. The abstract does not specify a particular vulnerable window or report the corresponding numerical results, so the available evidence does not establish when pollution exposure had the strongest association with low birth weight.

Mixed-exposure analyses were conducted using dual-pollutant models and weighted quantile sum regression. These models indicated that combined exposure to air pollutants during the first trimester, the second trimester and the full trimester was associated with higher odds of low birth weight. PM2.5 and CO contributed the most to the mixed-exposure association in the weighted quantile sum model. These findings concern statistical associations from observational analyses and do not demonstrate that pollution caused low birth weight.

Stratified analyses also reported associations between prenatal PM2.5 and CO exposure and higher odds of low birth weight among pregnant women younger than 35 years, although the abstract does not identify the exposure window for those subgroup estimates. Among pregnant women with gestational diabetes, exposure to PM2.5, particulate matter with an aerodynamic diameter of 10 micrometres or less and sulfur dioxide was positively associated with odds of low birth weight. The evidence summarized here comes from the study abstract, which does not describe exposure assignment, potential confounding, missing-data handling or other details needed for a full assessment. The retrospective, single-hospital design also limits how broadly the findings can be generalized. The authors proposed further research on the synergistic effects of multiple pollutants as a direction for future study, rather than as an additional result of the current analysis.

Subject of Research: Associations between prenatal air-pollution exposure and low birth weight in a retrospective Fujian cohort

Article Title: The association between air pollution exposure during pregnancy and low birth weight: a retrospective cohort study in southern China

Article References: Cai, Y., Lin, Y., Jiang, J., Li, H., Dong, Y., Zhang, Y., & Zhang, Q. (2026). The association between air pollution exposure during pregnancy and low birth weight: a retrospective cohort study in southern China. BMC Public Health. https://doi.org/10.1186/s12889-026-29842-4

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29842-4

Keywords: air pollution, pregnancy, low birth weight, PM2.5, carbon monoxide, Fujian, maternal health, retrospective cohort, mixed exposure, association, between, pollution