Children who are ostracized by their classmates or “picked on” by their teachers may be more likely than their peers to start having sex by the age of 13, a new study suggests.

Researchers found that of 312 Canadian children who were followed from kindergarten through seventh grade, 17 percent said they had started having sex by the end of the study period.

Among girls, those who’d been routinely ostracized by their peers were more likely to have started having sex. The same was true of boys and girls who’d been verbally abused by their teachers earlier in elementary school, the study authors report in the American Journal of Public Health.

They say that negative relationships with peers or teachers may encourage early sexual experimentation for a number of reasons.

Among girls in the study, for example, low self-esteem seemed to explain the link between peer rejection and early sex. Girls with a poor self-image may see sex as a way to become “popular,” according to the researchers, led by Dr. Mara Brendgen of the University of Quebec.

The relationship between verbal abuse by teachers and early sex seemed to be partially explained by delinquent behavior in seventh grade. That is, children who’d been “picked on” in earlier grades were more likely to get into fights, use drugs or alcohol, or steal by the time they were 13; these students, in turn, were more likely to start having sex.

However, delinquency was not the full explanation, Brendgen and her colleagues found. They speculate that other factors, like a diminished interest in school, might also be at work.

For parents, the findings highlight the importance of helping their children when they are having problems with their peers or teachers, according to Brendgen.

“If the child has trouble with classmates or teachers, but the school hasn’t contacted the parents about this issue, parents should contact the teacher,” she told Reuters Health.

But they should also be careful not to “lay blame” on anyone, Brendgen noted, and instead work with teachers to improve any difficulties their children are having.

Parents can also help younger children develop the social skills to make new friends, she said. “Even having a single good friend can protect children from the loneliness and depression feelings that result from rejection and victimization.”

The findings are based on interviews with 312 children at five Quebec elementary schools. From kindergarten through the fourth grade, the children were asked to name those classmates they “most liked” and “least liked” to play with. They were also asked to name classmates “who always get picked on by the teacher,” and which ones tended to get into fights and disrupt class.

In seventh grade, the students answered questions on their own self-esteem, any delinquent behavior and any sexual activity.

Regardless of other factors - like disruptive behavior in earlier grades - children who’d been picked on by their teachers were more likely to start having sex by the end of seventh grade.

According to Brendgen and her colleagues, additional training might help teachers find better ways to manage stressful classroom situations and children with special needs.

Teachers also need support, Brendgen said, which for some children means help from school psychologists.

SOURCE: American Journal of Public Health, November 2007.