Smoke in the Womb Makes Unruly Toddlers

A new study finds that unborn babies regularly exposed to cigarette smoke in the womb are much more likely to have behavioral problems as young children.

The study, detailed in current issue of the journal Child Development, is the first to show a link between smoking during pregnancy and child behavior problems in the first years of life.

The researchers found that 2-year-olds whose mothers were exposed to cigarette smoke while pregnant were nearly 12 times more likely to show clinical levels of behavioral problems compared to their unexposed peers.

The researchers looked at 93 children between their first and second birthdays. Forty-four were exposed to cigarette smoke before birth; among those exposed, nearly half of their mothers reported smoking more than half a pack a day.

As any parent will tell you, behavioral problems in toddlers are nothing new. There is even a name for it—the "terrible twos." But the behavior of toddlers exposed to cigarette smoke got progressively worse between 18 and 24 months of age compared to unexposed toddlers.

In psychology, symptoms of disruptive behavior include aggression, irritability, rule breaking and poor social skills. The exposed toddlers were significantly more likely to exhibit aggressive behavior and stubbornly refuse following directions. They were also less likely to seek out and socially interact with their mothers.

The one symptom that the exposed toddlers did not exhibit was increased irritability. This is important, the researchers say, because different components of disruptive behavior reflect functioning within different parts of the brain.

"By pinpointing which behaviors are involved, it sets the stage for the next set of studies which can more precisely characterize the relevant behaviors and their associated brain regions in exposed children," said study leader Lauren Wakschlag of the University of Illinois at Chicago.

Wakschlag and her colleagues previously found a link between prenatal smoking and antisocial behavior in older youth. The new study suggests that for some children, the roots of their behavioral problems might occur before they are born.

While the study supports the theory that smoking can lead to long-term problems later in life, Wakschlag cautions that it does not prove it.

"However, our findings do move us one step closer to answering this question by generating ideas regarding what areas of the brain might be affected by exposure," she said.