A hormone is released slowly and steadily through the walls of the capsules. While birth control pills usually contain an estrogen and a progesterone, the Norplant capsules contain only a type of progesterone. Norplant is effective as birth control because it stops the development and release of eggs from the ovary. It also has an effect on the mucous of the cervix, which makes it more difficult for sperm to enter the uterus. Norplant is effective as birth control 24 hours after insertion.
Nothing needs to be done on a daily basis or at the time of intercourse.
The capsules will provide birth control for five years. After five years, the capsules must be removed, but if the woman wishes to continue to use Norplant, a new set can be inserted. The capsules can be removed anytime the woman wishes to stop using the system. Fertility returns rapidly to normal once the capsules are removed. The skin on the inner part of the arm just above the elbow is first cleaned with an iodine solution.