Associations Between Prenatal Traffic-Related Air Pollution Exposure and Birth Weight: Modification by Sex and Maternal Pre-Pregnancy Body Mass Index

Environ Res. 2015 Feb;137:268-277. doi: 10.1016/j.envres.2014.10.035. Epub 2015 Jan 16.


Background: Prenatal traffic-related air pollution exposure is linked to adverse birth outcomes. However, modifying effects of maternal body mass index (BMI) and infant sex remain virtually unexplored.

Objectives: We examined whether associations between prenatal air pollution and birth weight differed by sex and maternal BMI in 670 urban ethnically mixed mother-child pairs.

Methods: Black carbon (BC) levels were estimated using a validated spatio-temporal land-use regression (LUR) model; fine particulate matter (PM2.5) was estimated using a hybrid LUR model incorporating satellite-derived Aerosol Optical Depth measures. Using stratified multivariable-adjusted regression analyses, we examined whether associations between prenatal air pollution and calculated birth weight for gestational age (BWGA) z-scores varied by sex and maternal pre-pregnancy BMI.

Results: Median birth weight was 3.3±0.6kg; 33% of mothers were obese (BMI ≥30kg/m(3)). In stratified analyses, the association between higher PM2.5 and lower birth weight was significant in males of obese mothers (-0.42 unit of BWGA z-score change per IQR increase in PM2.5, 95%CI: -0.79 to -0.06) ( PM2.5×sex×obesity Pinteraction=0.02). Results were similar for BC models (Pinteraction=0.002).

Conclusions: Associations of prenatal exposure to traffic-related air pollution and reduced birth weight were most evident in males born to obese mothers.

Keywords: Birth weight; Body mass index; Prenatal exposure; Sex; Traffic-related air pollution.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Air Pollutants / analysis*
  • Birth Weight / drug effects*
  • Body Mass Index
  • Boston / epidemiology
  • Environmental Monitoring
  • Female
  • Humans
  • Infant, Newborn
  • Male
  • Maternal Exposure*
  • Multivariate Analysis
  • Particulate Matter / analysis
  • Pregnancy
  • Pregnancy Outcome / epidemiology*
  • Sex Characteristics
  • Soot / analysis
  • Vehicle Emissions / analysis*
  • Young Adult


  • Air Pollutants
  • Particulate Matter
  • Soot
  • Vehicle Emissions