Can a woman get pregnant if she has ovulated already for the month?

Menses starts 14 days after ovulation. When menstrual periods vary in length it is always the time before ovulation that varies. So if you are regular and can predict when menses will start then you know you are going to ovulate 14 days before that. You are usually fertile 2-3 days before and after ovulation.

This information is best used to help a couple trying to conceive. Men are most fertile if they have been having regular ejaculations but take a break for 2-3 days. So the best way to conceive is to have intercourse regularly through the month then take a break for a few days and then make a point of having intercourse from 2-3 days before to 2-3 days after the predicted ovulation.

Women, even if usually regular, can ovulate early or late in any given month so this "rhythm method" (avoiding intercourse only during the fertile period) is not reliable as a form of contraception (Birth Control).