 [ Symptoms ] can i start a new pack of birth control late to move my next period a couple days and still prevent pregnancy  type tri sprintec i just want to push it a couple days for a new start date i am about to finish my sugar pills now [ Disease ] in short the answer is often a lot of couples trying to conceive spend a lot of energy timing sex with mathematical precision to the woman is ovulation theoretically the approach makes sense recent studies have shown the window of opportunity for a sperm to fertilize an egg is pretty small essentially it is only the four to five days leading up to ovulation and the day of ovulation itself your best chances are on the day before and the day of ovulation so the key would seem to be to have sex frequently in that five  to six day window but while timing your lovemaking exclusively to those few days makes logical sense it has some drawbacks    primarily because your body does not always behave with clockwork regularity even if your cycle is regular ovulation can occur at any time during the cycle if you are having sex on the day you think you are ovulating and you are off by a few days you may be out of luck so the expert advice is to hedge your bets have sex at least two to three times every week and if you have got the stamina why stop there studies have shown that as long as your partner has a normal sperm count having sex every day of the month further increases your chances