Yes, its not as likely to get pregnant while on your period, but IT CAN STILL HAPPEN. Do not use this as a form of birth control, because some women, although not as common, can occasionally ovulate while on their period. It's not worth the risk.
Precum can get you pregnant. Please do not use the pullout method as a method of birth control either. About 1/4th of the people using the pullout method will become pregnant within a year. If you are having sex and using these as methods, you should go to your obgyn or go to planned parenthood and get on some birth control (or use condoms if you don't feel comfortable using the pill).