Growing a Baby in Dirty Air

Air pollution during pregnancy may affect child behavior later in depressed moms

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) The environment around a pregnant woman can influence a growing baby. High levels of pollution may be one thing that affects a developing baby.

A recent study found that children had worse behavioral problems if their mothers had been depressed and around greater pollution levels during pregnancy.

The researchers focused on a group of pollutants called polycyclic aromatic hydrocarbons, or PAHs.

These are found in oil, coal and tar and are released when fuel from these products or other organic matter is burned.

Many of the behavioral problems in children only showed up among depressed moms if high levels of these pollutants were in the air during pregnancy.

"Avoid heavy air pollution while pregnant."

The study, led by Frederica Perera, PhD, of the Department of Environmental Health Sciences at the Columbia University Mailman School of Public Health, looked at the effects of car exhaust-related pollution on children's behavior.

The researchers followed 248 children of nonsmoking white women who lived in a part of Krakow, Poland where there was regular coal burning.

The children were followed from before they were born until they were 9 years old.

During the mothers' pregnancies, the researchers measured the mothers' exposure to PAHs (and therefore their unborn babies) by measuring the immediate air around the moms.

The researchers also studied the level of "demoralization" among the moms during pregnancy.

Demoralization means a person feels like they have lost hope or courage and are depressed.

Finally, the researchers compared these findings to the children's behavior between ages 6 and 9, according to a commonly used psychology tool for assessing child behavior.

The researchers found that higher levels of PAHs during pregnancy — combined with high levels of depression among the mothers — led to a greater number of behavioral problems among the children later on.

During the women's pregnancies, all of them had some exposure to PAHs, and 36 percent had exposure to secondhand tobacco smoke.

The average level of exposure to PAHs found among the women was a concentration of 20.7 nanograms per cubic meter (ng/m3). The range was from 1.8 to 323.8 ng/m3.

The average of PAH concentration in the area was about five times greater (4.9 ng/m3, compared to 0.9 ng/m3) in the winter time (heating season) than in the summertime.

The researchers measured ten different sets of behaviors among the children:

  • anxious/depressed
  • withdrawn/depressed
  • somatic complaints (aches and pains unrelated to a particular condition)
  • social problems
  • thought problems
  • attention problems
  • rule-breaking behavior
  • aggressive behavior
  • internalizing problems (being withdrawn, not participating)
  • externalizing problems (acting out, misbehaving)

Throughout the entire group of children, 13 percent showed symptoms of anxiety/depression, and 14 percent showed internalizing problems.

The researchers found that children whose mothers had more depressive symptoms and who were exposed to higher amounts of PAHs before birth were more likely than the other children to have anxiety/depression, be withdrawn/depression, social problems, aggressive behavior, internalizing problems and externalizing problems.

In addition, children whose mothers were depressed during pregnancy were only likely to show higher levels of anxiety/depression, withdrawn depression, rule-breaking, aggressive behavior, internalizing problems and externalizing problems if the children had also been exposed to higher levels of PAHs before birth.

In other words, if a child's mother had been depressed during pregnancy but had only been exposed to lower amounts of PAHs, the children were not at higher risks for those behavioral problems.

"The results provide the first evidence of an interaction between prenatal exposure to maternal demoralization and air pollution on child neurobehavioral development," the researchers wrote.

The study was published October 7 in the journal Pediatrics. The research was funded by the National Institute of Environmental Health Sciences. The researchers declared no conflicts of interest.

Review Date: 
October 7, 2013
Last Updated:
October 8, 2013