What are the benefits and risks of using the Depo-Provera (medroxyprogesterone acetate) injection as a birth control method for a healthy 35-year-old woman?

Depo-Provera (Depot Medroxyprogesterone Acetate) for Birth Control in a 35-Year-Old Woman

Depo-Provera is a highly effective contraceptive option for a 35-year-old woman, with a typical-use failure rate of approximately 6% and perfect-use failure rate of 0.2%, but she must understand the key risks: menstrual irregularities (nearly universal initially), potential weight gain, bone mineral density loss (which is largely reversible), and delayed return to fertility averaging 9-18 months after discontinuation. 1, 2

How Depo-Provera Works

• The injection contains 150 mg of medroxyprogesterone acetate given intramuscularly every 13 weeks (or 104 mg subcutaneously), which prevents pregnancy primarily by inhibiting ovulation 1, 2
• It also thickens cervical mucus to block sperm penetration and causes the uterine lining to become thin, preventing implantation 3
• The medication is detected in blood within 30 minutes and maintains contraceptive levels for approximately 3 months 3

Major Benefits

• Highly effective contraception that doesn't depend on daily adherence or remembering to take pills 1, 4
• Can be used by women who cannot take estrogen-containing birth control (such as those with high blood pressure, history of blood clots, or migraine with aura) 1, 4
• Reduces menstrual cramps and protects against iron-deficiency anemia 1
• Provides protection against endometrial cancer 5
• No interaction with most medications, making it suitable for women on various treatments 1

Critical Risks to Discuss

Menstrual Changes (Most Common)

• Nearly all women experience irregular bleeding initially—this includes unpredictable spotting, bleeding, or occasionally heavy bleeding 1, 2, 5
• Bleeding patterns typically improve over time: by 12 months, 55% of women have no periods, and by 24 months, 68% have no periods 5
• Pre-injection counseling about these changes significantly reduces discontinuation rates 1, 2
• If abnormal bleeding persists or becomes severe, medical evaluation is needed to rule out other causes 5

Bone Mineral Density Loss (FDA Black Box Warning)

• Depo-Provera causes reversible bone mineral density (BMD) loss, with the greatest decline occurring in the first 2 years of use 5
• Adult women show spine and hip BMD decreases of 5-6% over 5 years of use 5
• However, BMD substantially recovers after stopping the medication, with partial recovery occurring within 2 years post-discontinuation 1, 6, 5
• The FDA issued a black box warning recommending use for longer than 2 years only if other methods are inadequate, but the American College of Obstetricians and Gynecologists does not recommend limiting use to 2 years because preventing unwanted pregnancy outweighs BMD concerns 6, 5
• All users should take 1300 mg calcium and 600 IU vitamin D daily, perform regular weight-bearing exercise, and avoid smoking and alcohol to protect bone health 1, 2, 6
• At age 35, she should be assessed for other osteoporosis risk factors (family history, eating disorders, chronic steroid use, metabolic bone disease) before starting 6, 5

Weight Gain

• Weight gain occurs in some but not all women 1, 2
• Women who gain more than 5% of body weight in the first 6 months are at significantly higher risk for continued excessive weight gain with ongoing use 1, 2
• This is a common reason for discontinuation and should be monitored 1

Delayed Return to Fertility

• After stopping Depo-Provera, return to fertility typically takes 9-18 months, which is longer than other reversible methods 1, 7, 6
• This delay occurs while the uterine lining recovers and normal ovulation resumes 6
• Both intramuscular and subcutaneous formulations show similar delays 1
• If she desires pregnancy in the near future, this method may not be ideal 6

Other Potential Side Effects

• Headaches, breast tenderness, hair loss, and changes in sex drive may occur 6
• No increased risk of blood clots, unlike estrogen-containing birth control 1, 4
• No effect on blood pressure 4

Cancer Risks (Reassuring Data)

• No overall increased risk of breast, ovarian, liver, or cervical cancer 5
• Provides prolonged protective effect against endometrial cancer 5
• A slight increased risk of breast cancer (RR 2.0) was found only in women who started Depo-Provera within the previous 5 years and were under age 35—this does not apply to a 35-year-old woman 5

Practical Administration Details

• First injection must be given during the first 5 days of a normal menstrual period to ensure she's not pregnant 5
• Repeat injections are given every 13 weeks (91 days), with a grace period up to 15 weeks 1, 2
• Use backup contraception (condoms or abstinence) for the first 7 days after the initial injection 2
• If more than 2 weeks late for a repeat injection, she needs backup contraception for 7 days after receiving the late injection 2
• The subcutaneous 104 mg formulation is equally effective and can be self-administered at home if desired 2

Important Counseling Points

• Depo-Provera provides no protection against sexually transmitted infections—condoms should be used consistently for STI prevention 2
• Amenorrhea (no periods) after prolonged use is normal and not harmful, but if it persists beyond 18 months after stopping, further evaluation is warranted 7
• She should not assume amenorrhea means she's menopausal or infertile while using the method 7
• Short courses of estrogen or shorter injection intervals can help manage persistent irregular bleeding 4

Common Pitfalls to Avoid

• Don't delay starting the method due to concerns about bone density in a healthy 35-year-old without osteoporosis risk factors 6, 5
• Don't routinely monitor bone density or arbitrarily limit use to 2 years based solely on the FDA warning 2, 6
• Don't fail to counsel about menstrual irregularities before the first injection—this significantly improves continuation rates 1, 2
• Don't assume all women will gain weight—monitor at 6 months to identify those at risk 1, 2