Maternal exposure to fine particulate matter and brain-derived neurotrophic factor (BDNF) in the fetus: A prospective cohort study

Maternal exposure to ambient fine particulate matter (PM2.5) during pregnancy has been associated with impaired neurobehavioral development in children. However, the specific mechanism remains unclear. Brain derived neurotrophic factor (BDNF) is an important growth factor in the nervous system. We evaluated the associations of maternal PM2.5 exposures with fetal BDNF in the umbilical cord blood in a prospective cohort study. A total of 711 eligible mother-infant pairs from the Shanghai Birth Cohort were included in the current study. Daily maternal exposures to ambient PM2.5 were assessed with a gap-filling approach at 1 * 1 km2 resolution based on self-reported home addresses. The concentrations of BDNF in the cord blood were measured by ELISA. A linear regression model was applied to evaluate the association of maternal ambient PM2.5 exposure with fetal BDNF level at birth. The median concentration of BDNF was 13,403 pg/ml. Vaginal deliveries and female infants had higher BDNF levels than cesarean deliveries and male infants. One natural log (ln) unit increase in maternal PM2.5 exposure during the second trimester was significantly associated with − 0.20 (95% CI: −0.36, −0.05) ln-unit decrease in BDNF level in all births. These effects were stronger and more significant in vaginal deliveries and in male infants. Our study suggests that BDNF in the cord blood may serve as a potential biomarker in assessing the neurodevelopmental effects of maternal PM2.5 exposure.