Hormonal birth control can have varying effects on bone health. Some methods, particularly those containing estrogen, may help protect against osteoporosis, while others, like Depo-Provera, may increase your risk.

Osteoporosis is a condition that causes a loss of bone density. If you have osteoporosis, you’re more likely to experience bone fractures.

It’s important to note that the relationship between birth control and osteoporosis isn’t fully understood.

A 2022 review concluded that more rigorous, well-designed studies are necessary before researchers can confidently say which types of birth control may promote bone health and which types may be detrimental to bone health.

Research suggests that certain types of hormonal birth control, particularly those that include estrogen, can have a protective effect on bone health.

Estrogen is known to play a key role in maintaining bone density, which is why estrogen-containing contraceptives are thought to protect against osteoporosis. The lower your bone density, the more likely you will experience osteoporosis.

One example of estrogen-containing contraceptives is combined oral contraceptives (COCs), also known as “combination pills.” COCs contain both estrogen and progestin and are among the most widely used forms of hormonal birth control.

According to some research, like the 2022 review mentioned before, COCs can help maintain or even slightly increase bone mineral density in some people—particularly when taken around menopause.

However, COCs can be detrimental to bone density if you take it in your adolescence.

Some studies, like this 2022 study and this 2023 study, found that adolescents who used COCs for 2 years had lower bone mass than expected.

Both of those clinical studies were quite small, using 127 adolescents and 168 adolescents, respectively.

Some contraceptives have been shown to reduce bone density over time.

This is particularly true of the injectable Depo-Provera (depot medroxyprogesterone acetate or DMPA) — also known as “the shot.”

Depo-Provera is a progestin-only contraceptive. It may reduce your body’s estrogen production. Because estrogen is important for maintaining bone density, this type of contraception may be dangerous for your bone density.

This effect is particularly pronounced in younger people who have not yet reached their peak bone mass. Because DMPA suppresses estrogen production, the body’s ability to maintain bone density is compromised.

However, as the Royal Osteoporosis Society points out on its website, DMPA only slightly increases the risk of osteoporosis.

The American College of Obstetricians and Gynecologists noted that the Depo-Provera injection may slightly increase your likelihood of developing osteoporosis, but they suggest that this drawback is balanced against your likelihood of pregnancy using other contraception or no contraception.

While the risk of osteoporosis is something to be aware of, it’s also important to use an effective form of contraception if you’re trying to avoid pregnancy.

A 2019 review of studies found that progestin-only contraceptives did not seem to cause bone loss unless it led to significantly low estradiol levels. Estradiol is an important form of estrogen made by the body.

While hormonal birth control can influence bone health, it’s not the only factor that contributes to osteoporosis risk.

Some of these risk factors are out of your control, such as:

  • Age: Bone density naturally decreases with age. The older a person gets, the greater their risk for osteoporosis, especially if they haven’t built strong bones earlier in life.
  • Genetics: Family history plays a significant role in osteoporosis risk. People with a family history of osteoporosis or fractures are more likely to develop the condition themselves.
  • Chronic health conditions: Certain medical conditions, such as rheumatoid arthritis, thyroid disorders, and gastrointestinal diseases like celiac disease, can interfere with the body’s ability to absorb nutrients and maintain bone density.
  • Eating disorders: Eating disorders, particularly anorexia nervosa and bulimia nervosa, are associated with an increased risk of osteoporosis.
  • Medications: Certain medications, such as glucocorticoids (steroids), can also increase the risk of bone loss.
  • Hormonal changes: You’re more likely to develop osteoporosis during or after menopause. This is because your estrogen levels tend to decrease rapidly, which can affect bone health.

However, certain risk factors for osteoporosis may be more in your control. The following lifestyle factors reduce bone density:

  • smoking
  • excessive alcohol consumption
  • low calcium levels
  • low vitamin D levels

If you’re concerned about your bone density, you might benefit from doing strength training exercises, eating a balanced diet, and reducing your smoking or alcohol intake, if applicable to you.

The relationship between birth control and osteoporosis is not fully understood. Research suggests that different types of hormonal contraception can have different effects on your bone health.

While Depo-Provera and other progestin-only birth control is linked to a slightly higher risk of developing osteoporosis, it’s important to weigh up the risks of osteoporosis against the risks of unintended pregnancy.

Unintended pregnancies can also have a negative effect on your overall well-being, which is why it’s important to explore your contraception options with an expert.

If you’re at risk for developing osteoporosis, it’s important to talk with a healthcare professional before choosing a birth control method. They can help assess your individual risk factors for osteoporosis and recommend a contraceptive that aligns with your health needs.

Sian Ferguson is a freelance health and cannabis writer based in Cape Town, South Africa. She’s passionate about empowering readers to take care of their mental and physical health through science-based, empathetically delivered information.