When would my ovulation occur?

Patient: I am newly married and i got my menses last 7th june 2011 and i usually get my menses every 25th or 27th cycle..I want to know when my egg ovulate and when i should have sex to become pregnant.I mean at what date if i do i will have chance of giving birth

Doctor: Ovulation usually occurs around day 14th of a regular 28 day cycle (subtract or add days based on your cycle length). If your periods vary in length each time, you may take the average of previous 3 to 5 cycles and calculate the average length of your periods. No single date can be calculated, since ovulation time and day may be different every cycle. You may try for the baby a few days before as well as a few days after the estimated date of ovulation, because once deposited inside, sperms can live for up to 3 days to fertilize the ovum. Since you had your last period on 7th June, your most fertile days would fall between 15th to 22nd June.