A new study suggests that maternal exposure to air pollution, specifically particulate matter (PM2.5, PM10) and nitrogen dioxide (NO2), during the three months before conception may raise the risk of childhood obesity for up to two years after birth. The study, published on Thursday, was conducted by researchers from the US and China.
While previous studies have shown links between air pollution during pregnancy and health problems in children, including respiratory issues and a higher risk of chronic conditions like obesity, this new research focuses on the critical preconception period — the three months before conception.
Researchers highlight that exposure to environmental pollutants during this time could affect the health of sperm and eggs, which are nearing their final stages of development. The study, published in Environmental Research, analyzed data from 5,834 mother-child pairs from maternity clinics in Shanghai.
The findings showed that greater exposure to PM2.5, PM10, and NO2 during the preconception period was associated with higher body mass index (BMI) and BMI-for-age z-scores (BMIZ) in children. BMIZ is a standardized score comparing a child’s BMI with others of the same age and sex.
“These results stress that the three months before conception are crucial. People planning to have children should consider ways to reduce air pollution exposure to lower their child’s risk of obesity,” said Jiawen Liao, a postdoctoral research associate at the Keck School of Medicine, University of Southern California.
The study found that higher exposure to PM2.5 during this period was linked to a 0.078 increase in BMIZ at age two. Similarly, higher exposure to PM10 was associated with a 0.093 kg/m² increase in BMI at the same age. From six months onward, children exposed to higher levels of these pollutants before conception showed greater weight, BMI, and BMIZ growth rates.
“Though the effect size is small, the widespread nature of air pollution suggests that its impact on childhood obesity risk could be significant, even before pregnancy,” said Zhanghua Chen, assistant professor at the Keck School.
While the study is observational and more research is needed to confirm causation, the findings underscore the importance of minimizing air pollution exposure before conception. The researchers recommend that individuals take steps to reduce potential risks for themselves and their future children.
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