Kids Misbehaving Years After Mom Lit Up

Prenatal smoking linked to child conduct disorders regardless of rearing and environment

(RxWiki News) Giving a child the best shot at a healthy life starts with a healthy pregnancy. Smoking during pregnancy may do more than just physical harm to the baby — behavioral problems may surface years later in the child.

In a recent study, researchers followed a group of kids to see if being exposed to their mother's smoking in the womb was related to the kids' developing behavior problems. Some of the kids were raised by their biological moms, while others were raised by adopted moms, to control for environmental factors in behavior.

The results of this study showed that it didn't matter whether kids were raised by biological or adopted mothers, prenatal smoking by the mother while the child was in the womb was associated with misbehaving among 4- to 10-year-olds.

"Quit smoking, especially if you're pregnant."

Darya Gaysina, PhD, from the College of Medicine, Biological Sciences and Psychology at the University of Leicester in England, led a team of researchers to investigate whether maternal smoking during pregnancy had any influence on later conduct disorders in children.

According to these researchers, when pregnant women smoke, the oxygen supply to the fetus is reduced. Previous research has suggested that prenatal smoking (smoking while pregnant) can play a role in later conduct disorders in children. However, an argument can be made that conduct disorders develop from the environment in which the child is raised.

A unique element to this study was the inclusion of adopted children. The researchers tracked prenatal smoking in children who were raised in homes with either a biological mother or an adopted mother. This approach allowed the researchers to test for links between prenatal smoking and conduct disorders that can't be explained by the children's home environment alone.

For this study, the researchers used data from three ongoing studies in the UK, the US and New Zealand. The studies included 1,724 kids who were raised by their biological mothers and 552 who were raised by adopted mothers.

The UK study included kids who had been conceived with in vitro fertilization (IVF), with 175 not being genetically related to the mother and 36 not being genetically related to the mother or father.

Parents reported conduct problems appearing in their children between 4 to 10 years of age. Conduct disorder-related behaviors included impulsiveness, aggression, vandalism, stealing and lack of empathy towards others.

The researchers gathered data on how many cigarettes the mothers smoked each day during their pregnancies. Parents were also asked whether they shouted at, were critical towards or were physically aggressive with their children.

The results of this study showed that 50 percent of the kids raised by adopted mothers and 33 percent of kids raised by biological mothers in New Zealand were exposed to smoking in the womb.

In the US, 41 percent of kids who were raised by their biological mothers were exposed to smoking in the womb. In the IVF study, 6 percent of kids raised by their biological mothers and 4 percent raised by genetically unrelated mothers were exposed to smoking in the womb.

After adjustments for gender, socioeconomic status, environment, parental education and parental behavior, prenatal smoking was still linked to conduct disorders in the children. The severity of the conduct disorder also increased as the amount of prenatal smoking increased.

The authors concluded that prenatal smoking was related to the later development of conduct problems in kids, regardless of the child being raised by a biological or adopted mother.

"[W]e can now recognize that maternal smoking during pregnancy creates a population of individuals at greater risk for specific behavioral disorders," Theodore A. Slotkin, PhD, from the Department of Pharmacology and Cancer Biology at Duke University Medical Center in North Carolina, wrote in a related commentary.

This study was published in July in JAMA Psychiatry.

The Health Research Council of New Zealand, the Canterbury Medical Research Foundation and several agencies within the National Institutes of Health provided funding for this project. No conflicts of interest were reported.

Review Date: 
July 24, 2013