For most women, the chance of getting pregnant during your period is much less than at other times of the month. But it is never, ever impossible. You will hear this refrain a lot in this section – it is never, ever impossible. Getting pregnant requires a sperm and an egg, so if those two things are around, you can have a pregnancy.
If you have short menstrual cycles or irregular periods, there is even more of a chance that your body might send out an egg (ovulate) or that there might be an egg around when your period starts. The egg can live for several days, and not all women ovulate weeks before their period. Some ovulate much closer to the time that the period occurs. Plus sperm can live for days, even up to a week, in the nice, wet environment inside a woman’s body. Therefore the egg and the sperm could be around at the same time, which could lead to a pregnancy.
Some people attempt to use the ‘rhythm method’ to prevent pregnancy. In other words, they only have sex during the ‘safe’ days of the menstrual cycle, when the woman is less likely to have an egg around. If you have really regular periods, you keep track of them carefully and you can estimate the time when you ovulate by changes in the thickness of cervical mucus or body temperature, you might have a slightly better chance to avoid pregnancy for a while. But even when you are really careful about only having sex at ‘safe’ times, it is not a very effective method for preventing pregnancy. Timing your sex leads to pregnancies more often than using birth-control pills, condoms or injectable hormones. If you have sex without any of these other kinds of birth control, there is really no safe time to have sex. If you don’t want to get pregnant, use real birth control. And if you don’t want to get a sexually transmitted disease, you also need to use a condom. (See, we really do love condoms.)