You would think with the body expelling the uterine lining during your menstrual cycle that sex during menstruation should be the safest time to go unprotected, but that is not the case. Sperm can live inside the body for up to five days and that means pregnancy can occur after your period from sex that occurred during your period. It is also important to note that all fertility cycles are different. Ovulation can occur at irregular intervals and that means pregnancy can occur any at time immediately before, during or after menstruation.
There are medical professionals who will swear pregnancy is impossible during pregnancy. However, there are women who have become pregnant after unprotected sex during their period to counteract these claims. And in superfetation, a woman can become pregnant again during early pregnancy, even when the embryo has already implanted.
If you plan on having sex at any time and you don’t want to become pregnant, use birth control to prevent sperm from entering the vagina or coming in contact with the vagina at all and remember pre-ejaculate contains sperm so even if you plan on using the pull-out method there is a chance of pregnancy.