gynecology and obstetrics
Progestin Contraceptive Injections
Contraindications and adverse effects
There are few contraindications for progestin injections, and these are similar to Progestin-only oral contraceptives . Themost common adverse effectof progestin injections is irregular vaginal bleeding. In the 3 months after the first injection, approximately 30% of users have amenorrhea. Another 30% have spotting or irregular bleeding (usually light)>11 days per month. Despite these bleeding abnormalities, anemia does not usually result. With continued use, bleeding tends to decrease. After 2 years, approximately 70% of users have amenorrhea. Because DMPA has a long duration of action, ovulation may be delayed after the medication is discontinued. After the last injection, a regular menstrual cycle resumes in about half the women within 6 months and in about three fourths within 1 year. However, ovulation may be delayed for up to 18 months. After ovulation occurs, fertility is usually rapidly restored. For women using NET-EN, return to ovulation occurs more rapidly, with an average of 3 months, and return to fertility within 6 months ( References ). Women typically gain 1.5 to 4 kg during the first year of progestin injection use and continue to gain weight thereafter. Because changes in appetite rather than metabolism are thought to be responsible, women who want to use progestin injections are usually advised to limit caloric intake and increase energy expenditure. In some studies, 1 to 5% of women using DMPA reported depression or mood changes ( References ). However, baseline scoring before starting DMPA was not accounted for. In well-designed studies, no evidence of exacerbation of preexisting depression by DMPA was found ( Headache is a common reason for stopping progestin injections, but severity tends to decrease over time. Most women using progestin injections do not have headaches, and preexisting tension headaches or migraines usually do not worsen. levels are low due to progestin injection use, there is no evidence of increased fracture risk, and bone density scanning is not recommended ( References , Mild, reversible deterioration of glucose tolerance may occur. While it is known that DMPA can alter lipoproteins, lowering high-density lipoproteins (HDL) and increasing the ratio of low-density lipoproteins (LDL) to HDL, this effect appears to be temporary and improve within 36 months of DMPA use. A similar effect would be expected with NET-EN. Unlike estrogen-based methods, progestin injections do not increase the risk of hypertension ( References ). DMPA does not appear to increase the risk of breast, ovarian, or cervical cancer. 