hi , i m a male of 21 yr n i m having a loyalful relation with my partner , from a past year ago we r doing unprotected sex in starting she had taken ipill & as we started doing alternate days i had made her stop to take that , and we use to do unprotected sex &  doing also , but ther is not a single thing come to listen about any problem or pregnancy . so we bth are worried about that . we knw a single sperm can make a lady pregnanat . so y it is not happening in our case. . pls help us with your answer
Only intercourse during fertile period causes pregnancy not during the safe period. Fertile period lies on day 8 to day 21 of menses. So maybe you are not practicing in fertile period. But if not then there may be some fertility problem that may require complete infertility work up of both partners.