eli5: Why do hormonal IUDs take 7 days to start working whereas Copper IUDs start working instantly? And why is it 7 days? Can’t it be less or more? How is that calculated?
In: 0
Hormones need to build up in the body to be effective, to make mucus to keep sperm from getting through your cervix, and regulate periods etc. seven days is just the amount of time it is determined to have enough of the hormone to work.
Copper IUD’s work instantly because they just make the sperm swim wrong so you can’t get pregnant.
Copper is 99.9% effective. The most effective kind of birth control.
Latest Answers