Ambient air pollution, H19/DMR methylation in cord blood and newborn size: A pilot study in Zhengzhou City, China

Abstract

Prenatal exposure to air pollutants is believed to be associated with adverse birth outcomes. However, the potential mechanisms, especially the epigenetic modified effects, still remain unclear. This study was designed to explore the association of air pollution, H19/DMR methylation levels, and birth weight and length. A total of 527 mother-infant pairs were recruited from Houzhai Center Hospital, Zhengzhou. Air pollution data during the study period was collected. The methylation at H19 promoter region and H19 DMR in maternal and cord bloods were determined using real-time PCR analysis. Ridge regression was used to analyze the association of air pollutants exposure during gestation with H19/DMR methylation and birth weight and length respectively. Results showed that prenatal exposure to NO2 was associated with higher H19 methylation in cord blood. Whereas SO2 and PM10 exposure were associated with lower H19 and H19 DMR methylation respectively. After stratification by pregnancy trimesters, the association of H19 methylation in cord blood with PM10 exposure also was found. Furthermore, prenatal exposures to air pollutants also were associated with birth weight and length. Specifically, with the increase of maternal SO2 exposure during the entire pregnancy, birth weight and length significantly decreased. While birth weight and birth length were significantly increased with NO2 exposure. The stratified analysis also found the associations between PM10 exposure and birth sizes in different trimesters. In conclusion, the gene methylation level in cord blood might be associated with prenatal environmental exposures. Birth weight and length were associated with both prenatal environmental exposures and genetic factors.