It also thickens the cervical mucus. This keeps sperm from joining with an egg. Some researchers believe that implants also may work by preventing a fertilized egg from attaching to the lining of the uterus. Of every 10,000 women who use implants, only five will become pregnant in the first year of use. Left in place, they can protect against pregnancy for five years.
Implants provide no protection against sexually transmitted infections.
Most women can use implants safely. The capsules will be inserted under the skin of the arm you use least. Insertion takes about 10 minutes. Protection against pregnancy begins within 24 hours. Do not have implants inserted if there is a chance that you are pregnant.