Doctors used to tell couples to have intercourse before, during, or right after ovulation (when a ripened egg is released from the ovary), but they now know that women are most likely to get pregnant if they have sex in the 5 days before—or on the day of—ovulation, not after.
That’s because once an egg is released from the ovary, it’s receptive to sperm for only 12 to 24 hours. Sperm, meanwhile, can remain viable for days—and sometimes weeks—after intercourse. So the more sperm present prior to ovulation, the better your chances of conception. Even women with perfect 28-day cycles, however, can ovulate irregularly. For this reason, most OB-GYNs recommend that couples trying to conceive have sex every other day for at least several weeks midcycle, to maximize the chances of sperm being present when an egg is released.