The key for parents, experts say, is not just talking about sex, but being deeply involved in their children's lives. "The message to parents is: You matter," said Sarah Brown, director of the National Campaign to Prevent Teen Pregnancy. "You have not totally lost your teens to peers and popular culture."
By the time students are in the ninth grade, 34 percent of all teens have had sexual intercourse. That rises to 60 percent by 12th grade. But researchers found half of mothers of sexually active teens didn't realize their children were having sex. "Perhaps it's because they do not want to know," said Dr. Robert Blum, director of the University of Minnesota's Center for Adolescent Health and Development.
The knowledge gap goes both ways. The vast majority of mothers strongly disapprove of their teenager's having sex, but large numbers of teens don't realize how their moms feel.
The issue is important for a number of reasons. Teenage pregnancy lessens the chances of success for mother and baby alike. And those who start having sex earlier are likely to have more sexual partners and less likely to use contraception, putting them at risk for both pregnancy and sexually transmitted diseases.
The research released Wednesday was based on interviews with mothers and their 14- and 15-year-old children. It follows similar research published in 2000 of eighth through 11th graders and their mothers. It found that when families have meals together, when parents know where their children are and when they know their kids' friends, it's less likely that a teenager will have sex.
Wednesday's findings, being published in the Journal of Adolescent Health, showed no relationship between mothers' attitudes and whether their sons have sex, though the earlier research found that teenage boys who were close to their mothers also were less likely to have sex.
Both studies were based on the National Longitudinal Study of Adolescent Health, a massive federal investigation of teenage behavior. Wednesday's research examined interviews with 2,006 teens ages 14-15 who said they were virgins. The same teens were interviewed a year later, and 10.8 percent of the boys and 15.8 percent of the girls had had sex by the second interview.
Researchers at the University of Minnesota examined extensive interviews with their mothers to try to determine what made the difference between those who became sexually active and those who stayed virgins. The effects of fathers were not addressed because fathers were not interviewed.
They found mothers whose daughters were still virgins shared several qualities. They strongly disapproved of their daughters having sex. They were satisfied with their relationship with their daughters. They frequently talked with the parents of their daughters' friends. They also were more likely to have a college degree.
It points to involvement, Blum said. It means more, he said, when a parent asks, "How was your French test?" than when she asks, "How's school?"
Amie McLain, 18, a sophomore at Howard University, agreed. She said parents should ignore the look of boredom that teens have perfected. Talking to her mother, she said, helped her decide against having sex with a high school boyfriend. "Keep talking. We're listening even if you think we're not," said McLain, who served on the National Campaign to Prevent Teen Pregnancy's Youth Leadership Team.
When it comes to sex, parents should communicate their views and values consistently, Brown said. "It's about talking, not 'the talk' - the dreaded talk."
Other factors made no difference in teenage sex, including how religious the mothers were, how often they talked about sex or how uncomfortable they were talking about sex. Talking about birth control also did not appear to have any effect on teens' sexual behavior. The study found that moms were much more likely to talk about birth control to their sons than to their daughters.
The 2000 study, which examined eighth- to 11th-graders, suggested that teens don't always know that their mothers' disapprove of sex. Most mothers - 85 percent - strongly disapprove of their teen's having sex. But 30 percent of their teen daughters and 45 percent of their teen sons guessed otherwise. "Many teens do not get the message," Blum said.