Approximately 1% of US women elect to use injectable depot medroxyprogesterone acetate (DMPA). Intramuscular DMPA (150 mg) provides effective contraception for 12 weeks. A new, lower DMPA formulation at a 30% decreased dose (104 mg) administered subcutaneously is currently available. It has been demonstrated to be equally efficacious as the higher does. Although as yet no controlled trial has compared it directly to the 150 mg dose, anecdotally the side effects are similar.42 There is an increased risk of pregnancy if the injection is delayed to 14 weeks and if given beyond 12 weeks. In these cases, a back-up contraceptive should be used for two to four weeks. The lower dose, subcutaneous 104 mg medroxyprogesterone acetate injectable, FDA approved in 2004, is available as prefilled syringes that can be administerd into the thigh or abdomen every 12–14 weeks. It can be given by the clinician or the woman herself, much as individuals give themselves insulin. The dose does not need to be adjusted based on body weight. Fertility usually returns in four to nine months, but may take as long as 18 months. Duration of use is not related to the length of time before fertility returns. This is particularly effective if temporary excellent contraception is required as during the use of isotretinoin or other medicines, or while waiting for confirmation of vasectomy success. Side effects Menstrual disturbances are common. Bleeding can be treated with NSAIDs, combined combination oral contraceptives, or 7 to 13 days of oral estrogen. Amenorrhea is common; over half of women develop amenorrhea within the first year, and three-quarters after the second year. Weight gain has been an issue for many women. The average weight gain is 2 kg (5 lbs) during the first year of use and 5? kg (11? lbs) during the second year. Overweight and obese women have lower efficacy rates. Other side effects include bloating, decreased libido, dizziness, mood changes, acne, palpitations, depression, breast tenderness, and headache. Total cholesterol and LDL may increase while HDL decreases. Bone recovery Bone mineral density may be reduced in women younger than age 20 years. Duration of use also plays a role, and women who use this method for more than five years are at particular risk. In 2004, the FDA added a “black box” warning to the labeling indicating that women who use Depo-Provera contraceptive injection may lose significant bone mineral density; bone loss is greater with increasing duration of use and may not be completely reversible. It is unknown whether use of Depo-Provera contraceptive injection during adolescence will reduce peak bone mass and increase the risk for osteoporotic fracture in later life. Depo-Provera contraceptive injection should be used as a long-term birth control method (e.g. longer than two years) if other methods are “inadequate.” There is a relatively high rate of discontinuation from this method, perhaps because it is associated with irregular bleeding, weight gain, and increased headaches. Alternatives The availability of alternative contraceptive strategies should be discussed at each visit. Adolescents, in particular, may simply not return for a subsequent injection and yet fail to substitute an effective contraceptive.
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