Early Risk Factors Linked to Child Aggression
July 16, 2004
by Amy Norton

NEW YORK (Reuters Health) - The seeds of a child's aggressive behavior may be planted even before birth, according to a new study -- suggesting, researchers say, that interventions to prevent youth violence should begin as early as pregnancy.

The study of 572 families with a 5-month-old baby found that parents' behavior before and during pregnancy was related to the risk of their child becoming a physically aggressive preschooler.

Mothers who smoked during pregnancy, began having children at a young age, or had their own behavioral problems in youth were more likely to have a child who developed a habit of hitting, kicking, biting or bullying others.

In addition, 5-month-olds from dysfunctional families or whose mothers frequently lost their tempers were at greater risk of becoming physically aggressive before the age of 4.

The findings suggest that for such at-risk children, interventions to cut the odds of future aggression should begin as early as possible, said lead author Dr. Richard E. Tremblay of the University of Montreal in Canada.

In general, children seem to learn to control physical aggression in the preschool years, yet efforts to curb such behavior are normally targeted at school-age children, whose habits are more ingrained, Tremblay noted in an interview.

Earlier interventions -- such as home visits from nurses to new parents -- may be more effective, according to the researcher. He said the "best model to date" has been an intensive nurse visitation program that in an earlier study cut the risk of child delinquency.

Tremblay and his colleagues are starting a prevention experiment in which nurse home visits with a special focus on curbing physical aggression will begin in pregnancy. Part of the point is to help parents control their own aggressive behavior.

For the current study, reported in the July issue of Pediatrics, Tremblay's team interviewed parents of 5-month-old infants about their own school-age behavioral problems, as well as more recent factors such as mothers' smoking and drinking during pregnancy and current family conflicts.

Mothers were also asked to rate their infants' temperament and describe their parenting habits.

The researchers then surveyed the mothers about their children's physical aggression at three different ages, up till the children were between 3 and 4 years old.

Overall, about 28 percent of the children were rarely or never physically aggressive, according to the mothers' reports. The majority, 58 percent, became modestly aggressive as they grew older, while roughly 14 percent were deemed highly aggressive.

When other risk factors were considered, children whose mothers had significant behavioral problems as kids -- such as fighting, skipping school or getting into trouble with the police -- were three times more likely than others to become highly aggressive.

Similar effects were found when mothers started having children at age 20 or younger, or when they smoked during pregnancy. In addition, 5-month-olds exposed to family conflict or a mother's "coercive parenting" -- frequently getting angry about a baby's fussiness, for instance -- were more prone to aggression as preschoolers.

According to Tremblay, the roots of a child's violent behavior extend back to before pregnancy. Genes, parents' past behavior, and environment -- such as smoking during pregnancy or, later, parents' reactions to their babies' expressions of anger or frustration -- are all at work, the researcher noted.

"All of these affect the development of the brain and its capacity to regulate emotions, especially reactions to anger," Tremblay explained.

Past research has shown that physically aggressive school-age children are at high risk of becoming violent teenagers and adults. They are also more likely than their peers to abuse alcohol and drugs, develop depression or to grow up to become abusive or neglectful parents.

Source: Pediatrics, July 2004.