Can Having Sex One Day before an Expected Menstruation Delay

A late period can be caused by many reasons. Mental stress and anxiety can delay menstruation, for example. Having sex a day before an expected period will not delay menstruation. Pregnancy is the most common reason for late (missed) periods, but not in every case. You can take a pregnancy test to exclude pregnancy. If you are pregnant, conception would have occurred a couple of weeks before...not during the sex you had one day before your expected period.