What is it?
The intrauterine system is a T-shaped device that is inserted into the uterus by a health-care provider in an office or clinic. It contains a hormone that is released slowly over time and acts on the lining of the uterus.
How does it work?
The IUS causes changes in the chemistry of the lining of the uterus (womb) to decrease the sperm’s ability to fertilize an egg and to prevent implantation. It also thickens the cervical mucus making it difficult for sperm to reach the egg. In some women, the IUS may prevent the ovary from releasing an egg.
Does it prevent sexually transmitted infections?
Remember that most birth control or contraceptive methods will not protect a person from sexually transmitted infections (STIs). To reduce the risk of STIs, including HIV, use a condom with another method of contraception. This is referred to as dual protection.
To be effective, birth control must be used correctly and consistently. If you want to prevent pregnancy, choose a method that you and your partner will use every time you have intercourse.
Talk to your health-care provider or visit a sexual health clinic to find out what might work best for you and your partner.