A contraceptive implant is a small, flexible rod that is placed under the skin of a woman's upper arm. It releases hormones, typically progestin, to prevent ovulation and make it harder for sperm to reach an egg. The implant can provide effective birth control for up to three years. The procedure to insert the implant is quick and usually done in a doctor's office. It is a long-acting reversible contraceptive, meaning it can be removed at any time if a woman wishes to become pregnant. Side effects may include changes in menstrual bleeding and mood swings.