SAN DIEGO – The reasons why overweight and obese adolescent females are more likely to engage in risky sexual behaviors compared with their normal weight peers remain unclear, results from a large national study demonstrated.
Although previous studies have shown that overweight and obese adolescent females are more likely than their normal weight peers to have intercourse before age 13, have multiple sexual partners, and are less likely to use contraception, "they only imply association; they do not offer any insight into motivations and the underlying actions," Dr. Erin M. Swanson said at the annual meeting of the American College of Obstetricians and Gynecologists. "Our objective was to examine the association of weight with sexual practices, perceptions of sex, and motivations for contraception among adolescent females."
Dr. Erin M. Swanson
Dr. Swanson of the department of obstetrics and gynecology at Medical University of South Carolina, Charleston, and her associates performed a cross-sectional analysis of data from wave 1 of the National Longitudinal Study of Adolescent Health, which involved in-home interviews with 3,356 females in grades 7-12 during the 1994-95 school year. The interviews were 1-2 hours long and focused on survey questions regarding sexual perceptions and behaviors in adolescent females.
Dr. Swanson and her associates categorized study participants into three body mass index percentile categories: less than 85% of expected (normal weight), 85%-95% of expected (overweight), and greater than 95% of expected (obese). Self-esteem was divided into two categories: normal or low based on responses to the Rosenberg self-esteem scale, a validated instrument.
At baseline, the mean age of the females was 15 years, 71% were white, 16% were black, and 13% were Hispanic. In addition, 15% were overweight, 8% were obese, 18% met criteria for low self-esteem, and 37% reported having sexual intercourse. Of those who reported having intercourse, 76% reported being over age 13 at the time.
More than one in five overweight females (22%) and 23% of obese females had low self-esteem, compared with 17% of their normal weight peers, a difference that reached statistical significance (P = .03).
Logistic regression analysis revealed that, compared with their normal weight peers, overweight and obese females were more likely to have sexual intercourse before age 13 (odds ratio, 1.3 and OR, 2.1, respectively), become pregnant (OR, 1.8 and OR, 2.3), and less likely to use oral contraception regularly (OR, 0.44 and OR, 0.28).
In addition, obese females were 1.9 times more likely to have been forced to have sex, compared with their normal weight peers.
"Both race and self-esteem were evaluated as possible cofounders and determined to have no effect on the logistic regression model for the reported behaviors," Dr. Swanson said. "Interestingly, the rate of reported gonorrhea and chlamydia did not differ between weight classes."
When asked about their motivations to engage in sex, a significantly higher proportion of overweight and obese females compared with their normal weight peers chose the response option "your friends would respect you more" (P = .01), which suggests a peer influence, Dr. Swanson commented. "Interestingly, when these answers were compared with self-esteem, there was no difference [between weight groups]," she said.
When asked about their motivations to use birth control, a significantly higher proportion of overweight and obese females compared with their normal weight peers chose the response options "birth control is too much of a hassle to use" and "it is hard to get a boy to use birth control with you" (P = .01 for both).
While the motivation for overweight and obese females to engage in risky sexual behaviors remains unclear, "our findings suggest that peer influence may be significant," Dr. Swanson said. "An adolescent’s decision to engage in sex is likely multi-factorial, influenced by more than self-esteem and body image."
She went on to note that overweight and obese adolescent females "should be considered a vulnerable population. Clinicians should identify these patients and spend time exploring their thoughts about themselves, their peers, and their decisions to engage in sexual behaviors. It is our job to give accurate information, screen for and treat sexually transmitted infections, provide contraception, encourage parental involvement and, if needed, give good prenatal care. We as obstetricians and gynecologists have a unique opportunity and responsibility to care for, educate, and give feedback to adolescent girls to improve their overall sexual health."
Dr. Swanson said that she had no relevant financial conflicts to disclose.