Q: How long do sperm live? For how long after we had sex can it fertilize the egg?
A: Sperm can live in the right environment inside the uterus and the cervix for up to 5 days. That's why a woman can get pregnant if ovulation happens within 5 days after intercourse.
Sperm can live up to 5 days, but most will die within 1-2 days after ejaculation, even inside the uterus. In other environments, such as the vagina, sperm live only a few hours and outside the human body, exposed to the open air, they will usually die within minutes.
The egg, on the other hand, has a life-span of only about 12-24 hours at most from the time it bursts from the ovary. So, fertilization can occur anytime live sperm meet up with a live egg, which can happen even if the sperm are deposited up to five days in advance of ovulation.