Why are obese teens saying no to birth control?

Teen pregnancy in the United States is so not a thing of the past. In fact, roughly one in four young women will pull a Bristol Palin and get pregnant before age 20.

In order to understand why some teens are more at risk of becoming pregnant (i.e. less likely to use contraception) than others, researchers from the University of Michigan conducted a two-and-a-half-year study on 18-and-19 year-old women in the Michigan area.

The researchers asked 900 teenaged participants fill out weekly journal entries detailing their sexual habits, number of sexual parters, and what type of contraception they used, if any. Types of contraception included: intrauterine devices (IUDs), birth control pills or the patch, condoms (male or female), and withdrawal (not a solid method, mind you).

They also sat down with each of the women at the beginning of the study to talk about sexual history, relationship characteristics, and to assess socioeconomic demographics.

During this initial meeting, participants were also scored on their Body Mass Index and divided into three categories: normal weight, overweight, and obese. Researchers hypothesized, based on previous studies, that the obese young women would be less likely use any form of birth control compared to their normal weight counterparts throughout the study.

Turns out their hypothesis proved correct. After analyzing a year’s worth of journal entires (researchers focused on the first year when response rates were the highest, but note the findings didn’t change when accounting for the full length of the study) they found that, overall, obese young women were less likely to use any form of contraception compared to normal weight girls.

Breaking it down by the numbers:

Turns out, obese women only used contraception in 84 percent of the weeks compared to normal weight women who used some form of contraception in 91 percent of the weeks.

Not only that, obese teens were less likely to be uniform with their contraceptive use. Of those who did use contraception, only 68 percent did so consistently versus 78 percent of normal-weight teens.

Obese women were also much less likely to use oral contraceptive pills. Only 27 percent of obese teens were on the pill compared to 45 percent of normal weight participants.

Lastly, obese teens were more likely to have given birth at least once already. Seventeen percent reported having a live birth, versus only 11 percent of the normal weight young women.

Interestingly however, the obese teens were more likely to use condoms, than their normal weight counterparts (40 percent versus 31 percent respectively).

Why is this happening?

The researchers point out that obese teens are more likely to have low self-esteem and this can impact their sexual behavior and “lead to difficulty obtaining and using birth control,” explains Tammy Chang, a physician and professor at University of Michigan who led the study. For example, she says, “Obese adolescents may feel less comfortable asking clinicians for contraceptives or obtaining contraception from a pharmacy or over-the-counter retailer.”

Not only that, doctors themselves may play a role. “We also don’t know whether physicians treat obese adolescents differently than normal weight adolescents in regards to sexual health care,” she says.

This could explain why obese women were more likely to use condoms—often available in schools, pharmacies, and grocery stores—but not oral contraception which they would have to go to a doctor to receive a prescription for.

Another factor at play is socioeconomic status. “Lower levels of contraceptive use may also result from the same socioeconomic barriers and limited health literacy that facilitated development of obesity,” writes Chang in the study.

In other words the same lack of resources leading to obesity—less access to healthcare, fewer educational resources, less money—could also result in fewer contraceptive choices. Again, birth control requires a doctor’s visit, whereas buying a condom or getting one for free from a school nurse is less of a financial burden.

“Finally, we should consider whether public campaigns that target adolescents’ sexual health are effectively communicating to obese adolescents,” says Chang in an email to Fusion. For example she poses the question, “Do messages and announcements feature predominantly normal weight adolescents, with whom obese adolescents may not identify, or are they located in places that do not reach obese adolescents?”

All of these factors may be reasons why obese young women are not using contraception on the same levels normal weight women are—and thus puts them at greater risk for unplanned pregnancy.

Chang is hoping this study can shed some light on a growing problem so more physicians and educators can make changes accordingly.

“As a family physician that 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,” she tells Fusion. “These findings are important so I can tailor my care to empower all adolescents, including obese adolescents, to make healthier sexual choices.”

Taryn Hillin is Fusion’s love and sex writer, with a large focus on the science of relationships. She also loves dogs, Bourbon barrel-aged beers and popcorn — not necessarily in that order.