Clinical practice: Contraception in adolescents.

In affluent societies, median age at menarche has dropped to below 13 years. Younger age at menarche is associated with earlier sexual activity. To avoid unintended teenage pregnancies, barriers to contraception provision must be kept low, i.e. availability without prescription or through a low-threshold prescription system, low-cost options and long-term prescriptions or easy refills. Since many adolescents are (over)concerned about side effects, these should be addressed. A gynaecological examination prior to prescription is no longer recommended. All effective reversible contraceptive methods are available to adolescents: user-based hormonal contraceptives, trimonthly depot medroxyprogesterone acetate (DMPA), and long-acting reversible contraception (LARC). User-based hormonal contraceptives carry a small absolute risk of venous thromboembolism (~4 per 10,000 patient-years), but the risk is more than tenfold higher among young women with an inherited clotting defect. DMPA reduces bone mineral accumulation, but this is a reversible effect; the metabolic risks, including weight gain and insulin resistance, appear to be greater. LARC, including intrauterine contraceptive devices and the progestogen-containing implant, is gaining popularity among teenagers; abnormal bleeding is the main side effect. Any effective contraceptive should preferably be combined with consistent condom use to prevent sexually transmitted infections ("the double Dutch").