A study of nearly 1,000 Michigan teens found that sexually active obese adolescents were significantly less likely to use contraception than normal weight peers.
- Among obese adolescents who used contraception, researchers found that these teens were less likely to use contraception on a consistent basis.
- In a separate study, findings indicate that for U.S. women, giving birth as a teen is associated with subsequent overweight/obese status later in life.
A study of nearly 1,000 Michigan teens found that sexually active obese adolescents were significantly less likely to use contraception than normal weight peers.1
Among obese adolescents who did use contraception, researchers found that these teens were less likely to use contraception on a consistent basis, notes Tammy Chang, MD, MPH, MS, an assistant professor of family medicine at the University of Michigan Medical School and a member of the university’s Institute for Healthcare Policy and Innovation, both in Ann Arbor. For example, the data indicate these teens may use condoms, but not 100% of the time, she points out.
“As a family physician who cares for many adolescents, it is crucial for me to know who might be at increased risk for unintended pregnancy so that I can ensure that every adolescent gets the resources and care they need,” states Chang, who served as lead author of the research paper. “These findings are important so I can tailor my care to empower all adolescents, including obese adolescents, to make healthier sexual choices.”
Take a closer look
To conduct the study, researchers examined 26,545 weekly journal surveys measuring sexual practices and contraceptive use from a longitudinal study of 900 women ages 18-19 in Michigan. Scientists then analyzed the association between weight and sexual behaviors, with outcomes including 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 when contraception was used consistently.
The mean proportion of weeks in which adolescents reported sexual intercourse was 52%; there was no difference by weight status, the analysis indicates. Among weeks in which adolescents reported sexual activity, obese adolescents had a lower proportion of weeks in which 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, researchers note.1
Teens at risk
Teens, no matter their weight, are at a higher risk for unplanned pregnancy than adults. In the United States, the unplanned pregnancy rate is 82% for adolescents compared to 49% for adults,2 states Alison Edelman, MD, MPH, assistant professor in the Department of Obstetrics & Gynecology at Oregon Health & Science University School of Medicine in Portland. This rate puts teens at a high unmet need for contraception, she notes.
“Obese teens typically have not manifested the many co-morbidities associated with obesity, and thus their options for birth control are usually unrestricted,” states Edelman. “Long-acting methods like the intrauterine device and implant are 20 times more effective than shorter-acting methods in women, [and they] are safe to use in young women.”
Women of all ages face weight challenges, and the perception that weight has changed while using contraception is a common reason for women to stop their birth control method, observes Edelman. There is evidence that most methods don’t cause a change in weight; the one exception is that a certain sub-group of teens might be more susceptible to weight gain with the contraceptive injection (depot medroxyprogesterone acetate, DMPA, Depo Provera). Teens who demonstrate a 5% increase in body weight during the first six months of DMPA use might be at risk for continuing to gain while using this method,3 she notes. (Contraceptive Technology Update reported on the research. See “Predict later weight gain for teens taking DMPA?” June 2011.)
On the other hand, evidence clearly demonstrates that pregnancy adversely impacts a woman’s future weight especially if, after pregnancy, she doesn’t re-achieve her pre-pregnancy weight, Edelman observes. In a 2013 published study, Chang and fellow researchers examined whether teen birth is independently associated with overweight and obesity in a multiyear U.S. cohort using the 2001-2010 National Health and Nutrition Examination Survey, a nationally representative cross-sectional survey of the U.S. civilian, noninstitutionalized population. Their research indicated that for women in the United States, giving birth as a teen is associated with subsequent overweight/obese status later in life.4
- Chang T, Davis M, Kusunoki Y, et al. Sexual behavior and contraceptive use among 18 to 19 year old adolescent women by weight status: A longitudinal analysis. J Pediatrics 2015; doi:10.1016/j.jpeds.2015.05.038.
- Mosher WD, Jones J, Abma JC. Intended and Unintended Births in the United States: 1982–2010. Hyattsville, MD: National Center for Health Statistics; 2012.
- Bonny AE, Secic M, Cromer B. Early weight gain related to later weight gain in adolescents on depot medroxyprogesterone acetate. Obstet Gynecol 2011; 117:793-797.
- Chang T, Choi H, Richardson CR, et al. Implications of teen birth for overweight and obesity in adulthood. Am J Obstet Gynecol 2013; 209(2):110.e1-7.