Understanding Safe Sex During Menstruation: Myths vs. Facts

Question
Is there a time of the month when it is safe to ejaculate inside a woman and have her not get pregnant? My girlfriend insists she knows her body and that its completely safe cause she's not ovulating and she knows when she is. She says she wants to feel me ejaculate inside her I don't know why though cause she's never asked me to before and she's not on birth control I use condoms. Is what she's saying true?

Answer
Most women don't know when they're ovulating, although some do.  When a couple try to avoid having sex during a woman's fertile time, it's called the rhythm method of birth control.  It's one of the most unreliable methods of birth control.  Usually it's safe to ejaculate inside a woman while she's having her period, but any other time isn't usually very safe, and leads to a lot of pregnancies.