Subdermal implants that release progestin are inserted just under the skin and are good for five years. Injections of progestin last three months but can cause irregular bleeding, weight gain and a delay of return to fertility. The progesterone-releasing IUD doesn't seem to cause cramps but only lasts three years, and bleeding can be a problem. Oral contraceptive pills combining estrogen and progesterone are associated with regular, shorter periods with less cramping and protect against ovarian cancer, cardiovascular disease and osteoporosis if taken into a woman's 40s. When used properly, their rate of effectiveness improves.
Condoms have the added advantage of protecting against sexually transmitted diseases.
Hormonal emergency contraception is not 100 percent effective, can cause nausea and must be taken within 72 hours. Using periodic abstinence or withdrawal, about 50 percent of people get pregnant within a year. New products soon to be available include a contraceptive patch and a hormone-releasing IUD that lasts five years. Vaginal hormone-releasing rings are being developed, along with vaginal products designed to protect against sexually transmitted diseases. A small Australian study has investigated testosterone implants in men.