 [ Symptoms ] is it ever safe to have unprotected sex i have heard women cannot get pregnant right before their period is this true [ Disease ] while there are certain times during a woman is monthly cycle where she may be less likely to get pregnant this is a very unreliable method for preventing pregnancy first of all a woman would need to know when she is ovulating and most women cannot reliably tell and even if she can tell there is still a chance she could get pregnant even if she avoids sex for several days following ovulation i would not recommend this approach if you are trying to prevent pregnancy it has a high rate of failure also of course unprotected intercourse always runs the risk of transmitting stds such as herpes gonorrhea chlamydia and even hiv