For women, gaining weight is a common factor in the decision about whether to start or continue with contraception. For this reason, the Faculty of Sexual and Reproductive Healthcare (FSRH) wanted to deep-dive into the scientific research available in order to clarify whether weight gain really is an expected side-effect.
Interestingly, an assessment of existing studies found that women of reproductive age tend to gain weight over time regardless of use of any contraceptive method. While it was found that some users of contraception do gain weight during use, there is no evidence that any of the following types of contraception actually cause significant weight gain:
- Intrauterine contraception (the IUD and IUS)
- The implant
- The progestogen-only pill
- The combined pill
- The patch
- The vaginal ring
As for the contraceptive injection, the FSRH says there isn't sufficient data to firmly confirm or exclude a causative relationship between that and subsequent weight gain. "Women often tell us that they do not want to start or to continue contraception because they are worried that it will make them gain weight," says Dr. Sarah Hardman, Director of the FSRH's Clinical Effectiveness Unit.
"In studies, women gain on average a similar amount of weight over time whether they are using hormonal contraception or not. In other words, women may gain some weight during use of a contraceptive method, but so, on average, do women who are not using contraception."
After assessing all the available studies, the FSRH were able to conclude that it seems that weight gain while using contraceptive pills, the implant, or the hormonal coil is "not significantly different to weight gain with no contraception or non-hormonal contraception."
Of course, that's not disregarding the fact that some women may gain some extra weight while using contraception. It's just that a causative link cannot be explicitly proven.
"Effective contraception is really important to enable women to avoid unplanned pregnancies, and hormonal contraception can have additional benefits like helping with heavy, painful periods," points out Dr. Hardman.
"Women are all [unique]: not everyone has the same experience with any method of contraception. The studies confirm that weight change can vary widely between individual women using the same method of contraception (or none)."
If you feel your contraceptive method doesn't suit you, make sure you speak to your doctor about the different options available to you.
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