Currently, birth control implants use a thin rod the size of a matchstick to stop pregnancy for up to four years. The most common side effect is irregular bleeding.


How it works: A nurse or doctor inserts the implant under the skin of your upper arm where it releases progestin, which inhibits ovulation and thickens cervical mucus to keep sperm from entering the uterus.


Cost: Up to $800


Rate of effectiveness: 99 percent