%0 Journal Article
%T Injectable contraception: the USA perspective.
%A Kaunitz AM
%J IPPF Med Bull
%V 26
%N 6
%D Dec 1992
%M 12346920
暂无%X Depot medroxyprogesterone acetate (DMPA, Depo-Provera) is used for contraception by 8-9 million women in more than 90 countries, including the US, as of January 1993.  Pharmacologically active levels of DMPA persist for 3-4 months following injection.  A 150 mg dose is used most often for high contraceptive efficacy every 3 months.  Norethindrone enanthate (NET-EN, Noristerat) is somewhat less widely used and is not marketed in the US.  Injectables act primarily by inhibiting ovulation, lowering the levels of follicle-stimulating hormone and luteinizing hormone.  Approximately 50% of women using DMPA for 1 year report amenorrhea whose occurrence is less frequent with NET-EN.  Menstrual changes are the most frequent causes of discontinuation of injectables.  In cases of heavy bleeding it is appropriate to undergo gynecological examination to rule out unrelated conditions, such as vaginitis, cervicitis, or cervical lesions.  The use of conjugated estrogen (12.5-2.5 mg daily) for 10-21 days will minimize bleeding.  Some women using injectables experience headache, dizziness, bloating of the abdomen or breast, and mood changes.  Long-term use of DMPA or NET-EN can often result in 1-3 kg weight gain.  The WHO Collaborative Study of Neoplasia and Steroid Contraceptives was launched in 1979 to examine cancer risks with the use of DMPA in Thailand, Mexico, and Kenya.  The relative risk of breast cancer was 1.21, which was statistically not significant.  In women diagnosed with breast cancer under age 35, short-term exposure to DMPA was associated with a slightly increased breast cancer risk, which, however, was not associated with duration of use.  DMPA dramatically lowers the risk of endometrial cancer for at least eight years following discontinuation of its use.  DMPA did not alter the risk of cervical cancer.  Fertility returns in 70% of former users within 12 months; it is suitable for postpartum and lactating women, and provides other noncontraceptive benefits.