The implant is a flexible plastic rod about the size of a matchstick, which has a progestin hormone.
How does it work to prevent pregnancy?
It is placed under the skin of the woman’s arm and the hormone is slowly released into the body over three years. The hormone stops the ovary from releasing an egg, so there is no egg for the sperm to fertilize. The implant also causes thickened mucus in the cervix and changes to the lining of the uterus. All of these changes caused by Implenon make it less likely that a woman will get pregnant while she is using it.
How effective is it in preventing pregnancy?
The implant is extremely effective. Typically, none or 1 of 100 couples will become pregnant in the first year of having sex.
How effective is it in preventing STDs?
This method is NOT AT ALL effective in preventing STDs or HIV. If a person has sex, condoms must also be used to reduce the risks of STDs and HIV.
Other things to know about the implant:
- The couple does not have to remember to do something to prevent pregnancy
- It lasts 3 years, unless it’s removed sooner
- The woman must go to a doctor or clinic to receive the implant
- The implant must be inserted and removed by a health provider
- Many women do not have regular monthly periods
- Some women have headaches, emotional symptoms, or weight gain
Acknowledgement: This fact sheet was adapted from PlannedParenthood.org, and BigDecisions.org, websites that provide education about reproductive and sexual health.