Smoking in pregnancy tied to kids' conduct problems

Children of women who smoked cigarettes during pregnancy are more likely to have behavioral problems than those whose mothers didn't light up, says a new analysis.

"The evidence is emerging that smoking in pregnancy and the frequency of smoking in pregnancy is correlated with developmental outcomes after (children) are born," said Gordon Harold, the study's senior author from the University of Leicester in the UK.

Previous research has tied smoking cigarettes during pregnancy to behavior problems among children later on, but those studies couldn't rule out the influence of other factors, such as genetics or parenting techniques, researchers said.

For example, Harold and his colleagues write in JAMA Psychiatry that mothers who smoke during pregnancy are more likely to have parenting styles that condone acting out.

For the new analysis, the researchers pulled together data from three studies from New Zealand, the UK and the U.S. that asked women whether or not they smoked cigarettes during pregnancy. Parents and teachers then reported on children's conduct problems - such as getting in fights or having difficulty paying attention - between age four and 10.

The analysis also compared children who were raised by adoptive mothers to children who were raised by their biological mothers in an effort to tease out the influence of genetics and parenting styles on any link between prenatal smoking and behavior.

The researchers compared children's behavior scores to an average of 100, where higher scores indicate more conduct problems.

In studies that looked at women who raised their own biological children, those who didn't smoke during pregnancy had kids who scored about a 99, on average, compared to a score of 104 among children whose mothers smoked 10 or more cigarettes per day.

How Many Women Smoke During Pregnancy?

According to the 2008 Pregnancy Risk Assessment and Monitoring System (PRAMS) data from 29 states-

Approximately 13% of women reported smoking during the last three months of pregnancy.

Of women who smoked 3 months before pregnancy, 45% quit during pregnancy. Among women who quit smoking during pregnancy, 50% relapsed within 6 months after delivery.

For more statistics on smoking during pregnancy see: PRegnancy Risk Assessment Monitoring System (PRAMS) and SMoking, Data from 2000–2008.

That difference, according to Harold, would be noticeable in daily life.

Similar results were observed for children who were raised by adoptive mothers when researchers surveyed their birth mothers about smoking.