Women who have used hormonal birth control are significantly more likely to be prescribed weight loss injections later in life, according to a major study by Danish researchers. The study, published in Jama Network Open, found that women using hormonal contraceptives were up to 63% more likely to be prescribed slimming injections such as semaglutide (Ozempic and Wegovy) compared to those who had not used such methods.
For women who used multiple types of contraceptives throughout their lives, the risk of being prescribed weight loss treatments was more than doubled. While anecdotal reports of weight changes associated with birth control have been common, scientific evidence has been less conclusive until now. The study authors noted that their findings align with the experiences reported by many women globally.
A previous study published in the National Library of Medicine indicated that 73% of British women reported weight gain linked to taking the pill. Some experts hypothesize that hormonal fluctuations caused by birth control could lead to water retention and increased appetite.
In the Danish study, researchers analyzed the health records of nearly 250,000 women aged 12 to 49. The analysis included 22,694 women who had used semaglutide and 226,940 who had not. The study did not have access to all participants' BMI data, but it observed that 75% of those who used weight loss injections were either overweight or obese, compared to approximately 31.5% of women who did not use semaglutide.
The research examined various forms of hormonal contraception, including the combined pill (containing estrogen and progestogen), the mini pill (containing only progestogen), hormonal intrauterine devices (coils), implants, vaginal rings, and patches. The findings showed that users of the combined pill were 42% more likely to start semaglutide, while mini pill users were 55% more likely. Women using hormonal coils faced a 63% higher likelihood.
Switching between different contraceptive methods also showed a correlation. For instance, women transitioning from the combined pill to the mini pill were 64% more likely to use weight loss injections, and vice versa with a 70% increase. Those who switched from the combined pill to a hormonal coil had an 80% higher likelihood. The most significant association was observed in women who used multiple different contraceptives, showing a 111% increased likelihood of using semaglutide.
The study authors suggested one potential explanation for these findings is that women using contraceptives may have more frequent interactions with healthcare professionals, leading to increased opportunities to discuss and access weight loss treatments. Approximately a quarter of women in the UK aged 16-49 currently use hormonal contraception, with the combined pill being the most common method.