How long is Depo-Provera (medroxyprogesterone) injection effective?

Depo-Provera Injection Duration of Effectiveness

Depo-Provera (medroxyprogesterone acetate) injection is effective for 13 weeks (3 months) and requires reinjection every 12 weeks (84 days) to maintain contraceptive effectiveness. 1, 2

Administration Schedule and Timing

• The recommended dose is 150 mg administered by deep intramuscular injection in the gluteal or deltoid muscle every 3 months (12 weeks/84 days) 1, 2
• The repeat injection can be given up to 2 weeks late (14 weeks from the last injection) without requiring additional contraceptive protection 3
• If a woman is more than 2 weeks late (>14 weeks from the last injection), she can still receive the injection if it's reasonably certain she is not pregnant, but will need to use backup contraception for 7 days 3
• There are no time limits on early injections; they can be given when necessary (e.g., when a woman cannot return at the routine interval) 3

Efficacy and Mechanism

• Depo-Provera has a failure rate of less than 1% when administered on schedule 1, 2
• The contraceptive effect is achieved through inhibition of gonadotropin secretion, which prevents follicular maturation and ovulation, and causes thickening of cervical mucus 1
• After injection, medroxyprogesterone acetate concentrations increase for approximately 3 weeks to reach peak plasma concentrations 1
• The concentrations decrease exponentially until becoming undetectable between 120-200 days following injection 1

Return to Fertility After Discontinuation

• Return to fertility after discontinuation is delayed compared to other contraceptive methods 1, 4
• The median time for return to ovulation is approximately 30 weeks (7-8 months) after the last injection 5
• Studies indicate a wide variation in time to ovulation after the last injection, with the majority ranging from 15 to 49 weeks 3
• By 12 months after the last injection, approximately 97.4% of women will have returned to ovulation 5

Common Side Effects with Long-Term Use

• Nearly all patients experience menstrual irregularities initially, which typically improve over time 4, 6
• Amenorrhea becomes common with continued use, reported by 57% of women by the end of a year of treatment 2, 6
• Weight gain is a common side effect, particularly in women who show early weight gain (>5% at 6 months) 4, 3
• Long-term use is associated with decreases in bone mineral density, which prompted an FDA black box warning in 2004 4, 1
• Other common side effects include headache, nervousness, abdominal pain, dizziness, and asthenia 2

Special Considerations

• Pre-use counseling about potential menstrual changes is essential to improve continuation rates 6
• For patients using Depo-Provera beyond 2 years, measures to promote skeletal health should be recommended, including calcium and vitamin D intake, weight-bearing exercise, and smoking cessation 4
• The American College of Obstetricians and Gynecologists does not recommend limiting use to 2 years despite bone density concerns, as the benefits of preventing unwanted pregnancy generally outweigh the risks 4

Subcutaneous Formulation

• A lower-dose subcutaneous formulation (104 mg/0.65 mL) is also available and provides similar efficacy to the intramuscular formulation 5, 7
• The subcutaneous formulation suppresses ovulation for more than 13 weeks in all subjects and is not affected by body mass index or race 5