The question of whether birth control can structurally widen a person’s hips is common, stemming from body changes experienced after starting hormonal contraception. The synthetic hormones in contraceptives cannot influence bone growth or widen the hip structure after skeletal maturity is reached. Instead, the perception of wider hips is rooted in subtle, measurable changes to body composition, specifically how the body handles fat storage and fluid balance. Addressing this concern requires distinguishing between the rigid skeletal architecture and the more malleable soft tissues surrounding it.
Understanding Skeletal Maturity
The bony structure of the hips, known as the pelvis, develops and widens primarily during puberty, driven by natural hormones. Growth stops when the growth plates, areas of cartilage at the ends of bones, fuse into solid bone, indicating skeletal maturity. For most women, this fusion occurs between the ages of 14 and 20.
Once these growth plates have closed, the long bones, including the pelvic bones, cannot increase in size or width due to the hormones found in birth control. While pelvic width can increase very slowly with age, this gradual process happens over decades and is not acutely influenced by starting hormonal contraception. The synthetic hormones in birth control do not possess the biological power to reopen fused growth plates. Therefore, birth control cannot make the hip bones structurally wider.
Hormonal Impact on Fat Distribution and Water Retention
The perceived change in hip size is tied to changes in soft tissues, specifically fat (adipose) tissue and fluid retention. Hormonal contraceptives introduce synthetic versions of estrogen and progesterone, which can subtly alter where the body stores fat. Natural estrogen promotes a gynoid or “pear” shape, encouraging fat storage in the lower body, including the hips, thighs, and buttocks.
The synthetic hormones can sometimes cause a slight increase in overall body fat mass. This new accumulation often follows the typical female pattern of lower-body distribution, leading to the perception of wider hips. Studies on combined oral contraceptives show that while overall weight gain is often minimal compared to non-users, any weight gain that occurs is typically due to increased body fat. This increase in adipose tissue around the hip area contributes to the feeling of a wider profile.
Synthetic hormones can also affect fluid balance. Estrogen, particularly in older, higher-dose formulations, can cause the body to retain more water. This temporary fluid retention can manifest as bloating or swelling, often in the abdomen and lower extremities. This water weight, which is not actual fat gain, can increase measurements and create the sensation of being heavier or wider, especially in the initial months of starting a new method.
Comparing Different Contraceptive Methods
Not all hormonal contraceptives affect body composition equally, as the type, dosage, and delivery method vary significantly. Combined Oral Contraceptives (COCs), containing both estrogen and progestin, are generally considered weight-neutral in most modern low-dose formulations. Clinical trials found no consistent evidence that COCs cause a significant weight increase compared to non-hormonal methods.
The greatest evidence for changes in weight and body composition is linked to the progestin-only injectable, Depot Medroxyproxygesterone Acetate (DMPA), commonly known as Depo-Provera. DMPA users show a more robust weight gain and an increase in total body fat mass, often gaining several kilograms over a few years. This effect is significantly more pronounced than with users of other methods or non-hormonal contraception, and is sometimes attributed to appetite stimulation caused by the specific type and high dose of progestin.
In contrast, methods like hormonal intrauterine devices (IUDs) and implants deliver progestin more locally or at a very low systemic dose. These methods tend to have minimal impact on overall body weight and fat distribution. Comparative studies show that the mean weight change for hormonal IUD users is similar to that experienced by users of non-hormonal IUDs.
Addressing Body Changes and Concerns
When experiencing perceived body changes, it is important to separate potential contraceptive side effects from normal life changes. Weight gain and subtle shifts in body shape are common as people age, regardless of contraceptive use, due to changes in metabolism or lifestyle factors. It is possible that starting birth control simply coincides with a natural increase in body mass.
If noticeable changes in body composition, such as an increase in perceived hip width, are a concern, the user should monitor and track the change to understand its magnitude and timing. Maintaining a consistent diet and exercise routine can help mitigate any potential increase in fat mass.
If the changes are bothersome, discussing them with a healthcare provider is the appropriate next step. The provider can help rule out other causes and explore alternative contraceptive methods. For example, switching from a higher-dose or injectable method to a low-dose pill, patch, or localized hormonal IUD may alleviate the concern by offering a different hormonal profile.