Contact with an environmental pollutant in pregnancy phase may amplify the chances of mothers giving birth to babies, who are vulnerable to obesity, state researchers.
A study by Columbia University's Mailman School of Public Health found that pregnant women in New York City exposed to higher concentrations of chemicals called polycyclic aromatic hydrocarbons, or PAH, were more than twice as likely to have children who were obese by age 7 compared with women with lower levels of exposure.
PAH, a common urban pollutant, are released into the air from the burning of coal, diesel, oil and gas, or other organic substances such as tobacco.
"Obesity is a complex disease with multiple risk factors. It isn't just the result of individual choices like diet and exercise," said the study's lead author Andrew G. Rundle, Dr. P.H., a professor of epidemiology at Columbia's Mailman School of Public Health.
"For many people who don't have the resources to buy healthy food or don't have the time to exercise, prenatal exposure to air pollution may tip the scales, making them even more susceptible to obesity," they added.
For the study, the researchers recruited 702 non-smoking pregnant women through prenatal clinics at NewYork-Presbyterian Hospital and Harlem Hospital.
The women were 18-35 years old, identified themselves as either African-American or Dominican, and lived in areas in Northern Manhattan or the South Bronx that are predominantly low income. Over the course of two days during their third trimester, they wore a small backpack equipped to continually sample the surrounding air; at night they placed it near their bed.
Children of women exposed to high levels of PAH during pregnancy were nearly twice as likely (1.79 times) to be obese at age 5, and more than twice as likely (2.26 times) to be obese at age 7, compared with children of mothers with lower levels of exposure.
The 7-year-olds whose mothers were in the highest exposure group had, on average, 2.4 lbs. more fat mass than children of mothers with the least exposure.
"Not only was their body mass higher, but it was higher due to body fat rather than bone or muscle mass," said Dr. Rundle.
Fortunately, there are ways to reduce PAH exposure.
Certain fuels release more of the chemicals than others, explained Dr. Rundle, and efforts in New York City to take diesel buses off the streets and retrofit oil furnaces so they burn cleaner fuel is already starting to help.
The results have been published in the American Journal of Epidemiology.