Q&A: When is the best time to conceive?

The most rapid sperm can be found in the fallopian tube in minutes. Other sperm may become trapped in the cervical mucus and take up to five days to reach the egg in the fallopian tube.

An excellent study by Wilcox looked at couple in whom a single act of intercourse led to pregnancy. They found that the peak time for conception is to have intercourse two days before ovulation or one day before or on the day of ovulation. Pregnancy was still possible when intercourse occurred three to five days before ovulation. However, there were no pregnancies when intercourse occurred more than one day after ovulation.

If you have a 28- to 30-day cycle, the most likely time for ovulation will be day 14 to 16. Therefore your "peak fertile period" could start as early as day 12 and last as late as day 16. Using an ovulation predictor test can help narrow this down. Otherwise, a reasonable approach is to have intercourse every other day throughout the estimated fertile period. In this example, day 12, day 14, and day 16.