Linda Goodman says you can only get pregnant when the moon is in the same phase as it was on the day you were born. for example. i was born on a full moon and i can vouche that i get pregnant on full moons so it might be worth a look to find out what phase the moon was in when you were born and have unprotected sex then. (she is an astrologer) you can findout what phase the moon wa sin when you were born by checking an ephemeris