In this recurring guest column, Kate White, M.D., of Boston Medical Center, answers your questions on all things gynecology. As the author of the Mayo Clinic Press book Your Sexual Health, she’s ready to dole out wisdom on sex, periods, menopause and more. Submit a question here.
Q: One of my friends is convinced that if she has unprotected sex with her boyfriend during her period, she won’t get pregnant. I don’t think that’s right. Which one of us is correct?
A: You win this round; there’s no totally safe time to have penis-in-vagina sex and not get pregnant.
“You can’t get pregnant during your period” is a myth. The logic is alluring: If you have sex during your period, then you’re far away from the middle of your cycle when your ovaries release an egg. That timing should keep you safe, right?
Not necessarily. First, sperm are hardy creatures. They can live up to five days, waiting for an egg to appear. While menstrual cycles last 28 days on average, if you have a shorter cycle one month, sperm could live long enough to fertilize the egg. Plus, not all vaginal bleeding is your period. Even if you bleed like clockwork, you may have an episode of heavy spotting that you mistake for a period. When that happens, your mental math gets thrown off, and you could end up having sex right when you’re ovulating.
Fertility awareness methods of birth control can help you avoid getting pregnant by identifying the days in your cycle when pregnancy is possible. However, it’s possible for these days to overlap with a period, especially if your periods aren’t regular. This is why about 1 out of 4 people using this method will get pregnant each year. Anytime you have unprotected sex with a sperm-producing partner, you may get pregnant.
That said, there are plenty of ways to have sex and achieve an orgasm that don’t involve penis-in-vagina sex. So if avoiding pregnancy is important, think about expanding your definition of what sex is.
A version of this text appears in Dr. Kate’s book Your Sexual Health.
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