Can a woman conceive on her period day?

It is unlikely, but possible.

Sperm can live inside a woman's body for up to 5 days. If you have unprotected sex in the days leading up to your period, it's possible for the sperm to fertilize an egg that is released during ovulation, which usually occurs 14 days before the start of your next period.

However, the chances of conceiving on your period are much lower than on other days of your cycle. This is because the lining of your uterus is shedding during your period, and it is not in an optimal state for implantation of a fertilized egg.

If you are concerned about getting pregnant, it is best to use contraception every time you have sex, regardless of where you are in your cycle.