What are the pros and cons of the Depo Provera (medroxyprogesterone acetate) shot?

Depo-Provera Shot: Pros and Cons

Depo-Provera is a highly effective contraceptive (0.3% typical use failure rate) that offers significant advantages including convenience, non-estrogen formulation, and menstrual suppression, but carries important risks of bone mineral density loss, menstrual irregularities, and weight gain that require careful patient counseling before initiation. 1, 2

Major Advantages (Pros)

Contraceptive Efficacy

• Depo-Provera has a typical use failure rate of only 6% and perfect use failure rate of 0.2%, making it one of the most effective reversible contraceptive methods available. 2, 3
• Effectiveness is independent of daily adherence or coitus, requiring only injections every 13 weeks (up to 15 weeks). 1, 4

Clinical Benefits Beyond Contraception

• Improves dysmenorrhea and provides protection against iron-deficiency anemia through reduction in menstrual bleeding. 1
• Reduces risk of endometrial cancer with prolonged use. 1, 3
• May raise seizure threshold in epileptic patients and decrease sickle cell crises. 1
• Safe for lactating women without adverse effects on breastfeeding. 1, 5

Practical Advantages

• Does not contain estrogen, making it suitable for women with contraindications to estrogen (history of thromboembolism, migraine with aura, cardiovascular disease). 1, 6
• Convenient administration requiring only quarterly visits rather than daily pill-taking. 1
• Self-administered subcutaneous formulation (104 mg) now available, which shows higher continuation rates than provider-administered injections. 4
• Discrete method that is independent of intercourse. 6, 7

Major Disadvantages (Cons)

Bone Mineral Density Loss (Critical Warning)

• The FDA issued a black-box warning regarding significant BMD loss: adults experience 5-6% decline in spine and hip BMD over 5 years, with most pronounced loss in the first 2 years. 3
• Adolescents show even greater BMD decline (up to 6.92% at total hip over 4.6 years), which is particularly concerning during the critical period of peak bone mass acquisition. 3
• Partial recovery occurs after discontinuation, but longer duration of use is associated with less complete recovery during the 2-year post-therapy period. 3
• The American College of Obstetricians and Gynecologists does not recommend limiting use to 2 years, but BMD should be evaluated when long-term use is needed, and the method should only be used long-term if other methods are inadequate. 4, 3
• All patients must receive counseling on skeletal health measures: 1300 mg calcium daily, 600 IU vitamin D, regular weight-bearing exercise, and smoking cessation. 1, 4

Menstrual Irregularities

• Nearly all patients initially experience menstrual cycle irregularities including irregular bleeding, spotting, or heavy bleeding. 1
• By 12 months, 55% of women experience amenorrhea; by 24 months, 68% experience amenorrhea. 3
• Irregular bleeding typically improves over time and may be managed with NSAIDs for 5-7 days for spotting or light bleeding. 4
• Pre-injection counseling about menstrual changes significantly improves continuation rates. 1

Weight Gain

• Weight gain is a common concern, though evidence shows significant variability between individuals. 1
• Studies show that 21% of adolescents experience early weight gain (>5% increase at 6 months), and these "early gainers" continue to gain weight over 18 months. 1
• Weight gain at 6 months is a strong predictor of future excessive weight gain with ongoing use. 1

Delayed Return to Fertility

• Return to fertility is delayed 9-18 months after discontinuation while the endometrial lining recovers and ovulatory function returns. 1, 4
• This delay occurs with both subcutaneous and intramuscular formulations. 1

Other Side Effects

• Headache, breast tenderness (mastalgia), hair loss, and changes in libido may occur. 1, 6
• Potential increased risk of venous thrombosis in patients at risk for estrogen-related complications, though advantages still outweigh risks. 1

Absolute Contraindications

Depo-Provera should not be used in patients with: 8

• History of stroke or myocardial infarction
• Pulmonary embolism or deep vein thrombosis
• Active smoking combined with other cardiovascular risk factors
• History of neurofibromas or meningiomas (may stimulate tumor growth)
• Undiagnosed vaginal bleeding, known or suspected breast malignancy, thromboembolic disorders, cerebral vascular disease, or liver dysfunction 9

Special Populations Requiring Caution

Strongly consider alternatives to Depo-Provera in patients with: 1

• Metabolic bone disease
• Chronic alcohol or tobacco use
• Eating disorders (anorexia nervosa)
• Strong family history of osteoporosis
• Chronic use of drugs that reduce bone mass (anticonvulsants, corticosteroids)
• Non-ambulatory disabled adolescents (levonorgestrel IUD preferred to avoid bone density effects)

Administration Guidelines

• Administered as 150 mg intramuscularly or 104 mg subcutaneously every 13 weeks. 1, 2, 4
• Can be given up to 2 weeks late (15 weeks from last injection) without requiring backup contraception. 4
• Backup method (condoms or abstinence) required for first week after initial injection. 1
• Self-administered subcutaneous formulation requires instruction on injection technique, sharps disposal, and access to reinjection reminders. 4

Cancer Risk Profile

• Slight or no increased overall risk of breast cancer in most users. 3
• Relative risk of 2.0 for breast cancer in women who initiated use within previous 5 years. 3
• Subgroup analysis shows RR of 2.19 for women under 35 years whose first exposure was within previous 4 years (attributable risk of 31.8 per 100,000 women per year). 3
• No increased risk of ovarian, liver, or cervical cancer. 3, 9
• Prolonged protective effect against endometrial cancer. 3, 9