Sexual Behavior and Contraceptive Use among 18- to 19-Year-Old Adolescent Women by Weight Status: A Longitudinal Analysis

To describe the association between weight status and sexual practices among 18- to 19-year-old women.
Study design
We analyzed a population-based longitudinal study of 18- to 19-year-old women residing in a Michigan county at cohort inception. Weekly journal surveys measured sexual practices, including contraceptive behaviors. Outcomes included proportion of weeks with a partner, proportion of weeks with sexual intercourse, number of partners, average length of relationships, proportion of weeks with contraception use, and proportion of weeks where contraception was used consistently. We examined 26 545 journal surveys from 900 women over the first study year. Ordinary least squares regression models for each outcome examined differences by weight status, controlling for sociodemographic characteristics.
The mean proportion of weeks in which adolescents reported sexual intercourse was 52%; there was no difference by weight status. Among weeks in which adolescents reported sexual activity, obese adolescents had a lower proportion of weeks where any contraception was used compared with normal weight adolescents (84% vs 91%, P = .011). Among weeks in which adolescents reported sexual activity and contraceptive use, obese adolescents had a lower proportion of weeks with consistent contraceptive use (68% vs 78%, P = .016) and oral contraceptive pill use (27% vs 45%, P = .001) compared with normal weight adolescents. All other relationships by weight status were not statistically significant.
In this longitudinal study, obese adolescent women were less likely to use contraception, and less likely to use it consistently when compared with normal weight peers. Findings suggest obesity may be an important factor associated with adolescent women's sexual behavior.