The study of more than 3,000 female students appears in the American Journal of Health Behavior.
Having sexual intercourse with multiple partners increases the risk of pregnancy, sexually transmitted diseases and resulting damage to reproductive health. Other studies have shown that girls are starting to have sex at younger ages, and an earlier start to sexual intercourse often leads to multiple sexual partner behavior.
Donna E. Howard, Dr.P.H., and Min Qi Wang, Ph.D., of the University of Maryland, based their study on information from the 1999 National Youth Risk Behavior Survey. Out of the total of 15,349 high school students who participated in the national survey, Howard and Wang focused on the 3,288 girls who reported ever having sexual intercourse.
Among these sexually experienced adolescents, Howard says, 24 percent reported no sexual partners in the past three months, about 63 percent had one and 13 percent had two or more recent sexual partners.
Besides fighting, drinking and substance abuse, girls with multiple sexual partners were also likely to have had unprotected sex the last time they had sexual intercourse, another dangerous behavior that only compounds the risks of sex with many partners.
Sexually active girls increasingly limited themselves to just one recent partner as they progressed through high school, she notes. Ninth graders reported more recent multiple sexual-partner behavior, but then odds of having more than one partner declined for girls in the 11th and 12th grades.
One possible explanation, Howard says, is that the younger adolescents may be experimenting with their sexuality and intimacy while, by the late years of high school, they may be involved in stable, longer-term dating relationships.
While this may seem small encouragement to worried parents, it underscores the necessity to examine sexual risk behaviors grade by grade. Howard says that educating girls before ninth grade may pay off in reduced sexual activity and its negative health consequences. Ninth grade marks an important transition for girls, she says. Not only must they deal with a new school, but they may also meet and date older boys, and be exposed to changing norms and pressures about sex.
Howard further notes that since risky behavior is more common among dropouts or teens who are absent frequently from school, her findings may actually underestimate the problem.