Designing effective ways to reduce both teen pregnancy and unsafe sex requires knowing how many girls are actually having sex and using contraception.
A recent study looked at how many girls at each age of their preteen and teen years had had sex. The researchers also looked at these girls' pregnancy rates and use of contraception.
The researchers found that very few preteen girls were sexually active. However, those who were sexually active were often forced into sex their first time.
They also found that girls were less likely to use contraception the younger they were when they first had sex, regardless of whether it was consensual or not.
The study, led by Lawrence B. Finer, PhD, of the Guttmacher Institute in New York City, aimed to understand the sexual behaviors of young girls.
Researchers already know that 18 percent of teens under age 15 have had sex, leading to about 16,000 pregnancies a year in this age group. Among girls aged 15 to 17, 30 percent have had sex and about 252,000 get pregnant each year.
Dr. Finer and his colleague investigated data from the National Survey of Family Growth to learn about sexual behaviors and experiences of girls aged 10 to 19 so they could compare the younger girls to the older girls.
Then they looked at the pregnancy rates among girls at each age using data from the National Center for Health Statistics and the US Census Bureau.
The results for the years 1984 through 1993 showed that very few preteens were having sex. Only 0.3 percent of 10-year-olds, 0.6 percent of 11-year-olds and 1.3 percent of 12-year-olds had had sex.
However, the younger the children were, the less likely it was that they had chosen to have sex, at least their first time. Among 10-year-olds, 62 percent of the girls who had had sex lost their virginity during nonconsensual sex.
Half of the 11-year-olds had been raped the first time they had sex, and 23 percent of the 12-year-olds had been raped the first time they had sex.
The rates of sexual activity increased as the girls got older. About 8.6 percent of 14-year-olds, 19 percent of 15-year-olds, 32 percent of 16-year-olds, 47 percent of 17-year olds and 60 percent of 18-year olds had had sex.
Pregnancy rates among very young teenagers were very low. For example, the researchers found that only about 1 in 7,000 girls aged 12 became pregnant each year.
In general, the researchers found that girls from age 15 up to 19 had similar patterns in their use of contraception.
However, girls who began having sex when they were 14 or younger tended not to use contraception the first time they had sex. They also did not start using contraception during sex until later on in their teens, compared to the girls who started having sex at an older age.
"Teaching young adolescents about contraceptive methods and prescribing or offering methods before they are likely to become sexually active is prudent: Knowledge of and access to contraception at an earlier age would help those adolescents who initiate sex early, and would likely increase contraceptive use among older teens as well," the researchers concluded.
"No study of sex education programs to date has found evidence that providing young people with sexual and reproductive health information and education results in increased sexual risk-taking," they wrote.
The study was published April 1 in the journal Pediatrics. The research was funded by the National Institutes of Health. The authors declared no conflicts of interest.