No STD protection. No one else can tell that the woman is using contraception. Long-term yet reversible. The woman has to remember only to return for her next injection. Changes in menstrual bleeding are normal such as light spotting at first and no periods after the first year of use.
Some women gain some weight.
If stopping to become pregnant, average 4 months longer wait before pregnancy than after other methods. Norplant Implants Small plastic capsules placed under the skin of a woman's arm slowly release a hormone. The hormone thickens cervical mucus so sperm cannot pass. Sometimes also stop ovaries from releasing eggs. No STD protection.