The progestin released by the hormonal IUD prevents fertilization by making the mucus in the
cervix thick and sticky, so sperm can't get through to the
uterus. The progestin and IUD change the uterine
lining, preventing implantation in the rare case that fertilization
The copper in the copper IUD is toxic to sperm. It causes
changes in the uterus and fallopian tubes that kill sperm. The IUD changes the
uterine lining, which prevents implantation in the rare case that fertilization
How this information was developed to help you make better health decisions.