Concerns about weight gain may have a significant influence on birth control choices, according to a new study at Pennsylvania State College of Medicine. The findings show that women who are overweight or obese are less likely than normal weight or underweight women to take birth control pills or other forms of hormonal contraceptives.
Weight gain is one of the most commonly reported reasons why women stop using hormonal contraception, and therefore may play a role in the risk of unplanned pregnancies, said Dr. Cynthia H. Chuang, professor of medicine and public health sciences at Pennsylvania State.
Although oral contraception has not been proven to cause weight gain, many women attribute increasing weight to the pill. The birth control shot, however, has been linked to weight gain in younger women.
For the study, the researchers wanted to determine whether women’s weight or their perception of weight influenced the type of birth control they used, if any. They examined demographic and survey data from nearly 1,000 privately insured women in Pennsylvania.
The researchers placed participants in weight categories based on body mass index (BMI), a measure of body size based on height and weight.
They found that overweight and obese women were more likely than healthy-weight women to choose forms of birth control known as long-acting reversible contraceptives (LARCs), and less likely to use methods like the pill, the shot, the patch and the ring.
Long-acting reversible contraceptives include intrauterine devices, commonly known as IUDs, and the contraceptive implant. LARCs do not contain estrogen, which some some women believe causes weight gain.
Overweight and obese women were also slightly more likely to use non-prescription methods such as condoms, withdrawal, and natural family planning, or no method.
“What we think may be happening is that women who are overweight and obese may be more likely to choose methods other than the pill or the shot because of fear of weight gain,” Chuang said. “As a result, they are choosing both more effective methods (LARCS) and less effective, non-prescription methods.”
Overall, 23 percent of overweight and 21 percent of obese women used LARCs, which are the most effective forms of birth control. In contrast, only six percent of underweight and normal weight women used LARCs in the study.
“We were actually glad to see that overweight and obese women were at least more likely to choose LARCs because I was expecting to see these women more likely to use non-prescription methods,” Chuang said.
Heavier women also were more likely than normal-weight women to use less-effective non-prescription birth control methods such as condoms or no method at all. However, these results did not reach statistical significance, Chuang said.
The researchers also wanted to see whether perception of weight influenced contraceptive choice. In the study, half of the women perceived themselves to be overweight, although only around 42 percent of them were overweight or obese based on BMI. This perception, however, did not appear to influence birth control choice.
“Women may be worried about weight gain when they’re making decisions about birth control, so clinicians need to be aware of that,” Chung said. “It could be an opportunity to counsel women about LARCs, which are more effective forms of contraception.”
The findings are published in the journal Contraception.
Source: Penn State