Can You Get Pregnant on Your Period?

Understanding your menstrual cycle is key
woman in bathroom holding pregnancy test

Your period came, so does that mean you can be a little more lax about birth control? After all, you can’t get pregnant while Aunt Flo is around, right?

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Unfortunately, that’s not true. You can get pregnant during your period.

  • If you didn’t ovulate in the middle of your cycle.
  • If your periods aren’t regular — so you don’t ovulate regularly.
  • If you have a short menstrual cycle.

It’s not quite that simple, says Ob/Gyn Amy Stephens, MD. She clears up the confusion about fertility and your monthly cycle.

Fertility windows

The most fertile time of your cycle, when you are most likely to get pregnant, is when you ovulate, or release an egg, Dr. Stephens explains. That typically happens midway between periods.

So if you have a regular 28-day cycle, Day 1 would be the first day of your period, and you would ovulate around Day 14. “You have the highest chance of getting pregnant during the few days before and after that day,” she says.

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But that’s a general guideline and not a rule. “You can definitely get pregnant outside that window,” Dr. Stephens says.

Ovulation timing

If you have unprotected sex during or right after your period, there is a lower chance of getting pregnant. “But the chances are not zero,” Dr. Stephens stresses.

That’s especially true for women with irregular periods, whose ovulation date is harder to predict. Even women who normally have periods like clockwork can experience an unpredictable cycle as the result of things like stress, hormonal changes, and losing or gaining weight.

Having a shorter-than-average cycle also increases your risk of conceiving during period sex. That’s because sperm can live inside you for up to 5 days. They could still be hanging around, looking for love, if you release an egg 4 or 5 days after your period ends.

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How not to get pregnant

If you want to get pregnant, plan to get frisky halfway between periods for the best chances. But if you’re trying to avoid pregnancy, don’t use your period as a guide. Instead, choose a reliable form of birth control.

“That’s the best way to prevent pregnancy,” Dr. Stephens says. 

Yeah, you probably already knew that. But now you know the whole story.

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