First regularise your cycles... Consult nearest gynecologists they will find the cause for your irregular cycles and treat accordingly... Once the cycles regularised woman gets pregnant around the days when ovulation occurs. The average time of ovulation is the 14th day of an average length (28 day) menstrual cycle. Ovulation time vary for each individual, and can occur from 12th to 19th day of the cycle . Sperm can live up to 3 to 5 days in a womans reproductive tract, so it is possible to become pregnant if unprotected sex occurs 5 days before ovulation..