How long can sperm live for? And can sperm survive during a period?

4-5 days and no. When sperm are deposited into the vagina they quickly move into the cervical mucus to avoid the acid ph of the vagina. Once in the cervical mucus the sperm swim through to the uterus and up to the egg over the next few days. Good cervical mucus is usually only present for 1-3 days before ovulation. After ovulation the mucus is thick and during a period the mucus is gone.