Can You Get Pregnant on Your Period?

Here's what an ob-gyn wants you to know about unprotected sex and that time of the month.

Periods come with enough to stress out about. Cramps, cravings, and mood swings are just a few of the not-so-fun symptoms of your monthly menstruation. So you would think the one thing you could relax about is knowing you're probably safe from getting pregnant, right? Wrong. Even though you and your S.O. may be totally cool with period sex, it doesn't necessarily mean that it's totally risk-free.

So can you get pregnant on your period? The short answer is yes, it is possible—for two reasons.

Not All Bleeding Is Your Period

"Every period is a bleed but not every bleed is a period," Amanda Kallen, MD, assistant professor of obstetrics, gynecology, and reproductive sciences at Yale School of Medicine told Health. Dr. Kallen explained that a period is the bleeding you experience for two to seven days at the end of a menstrual cycle. This means that a woman is not pregnant, but is now starting her cycle over again, and will ovulate in a few weeks.

However, said Dr. Kallen, there are other reasons you might bleed from your vagina. Irregular cycles, polyps, and early pregnancy symptoms can all cause bleeding and can be mistaken for a period.

"The risk here is that bleeding could be interpreted as a real period," said Dr. Kallen. "A woman might think she is totally safe, but she's not actually in that 'safe' part of her cycle."

Timing Is Crucial

So what about when a person is actually on their period? Dr. Kallen said that another possible way a person can get pregnant during her period is if they have a longer menstrual cycle that lasts right up to when they begin ovulating.

"If [a woman] has sex at the very end of her cycle and happens to ovulate on the earlier side, sperm could still be in her reproductive tract and she could conceive even though she had sex on her period because they can live for several days there," said Dr. Kallen.

Because sperm can live for up to five days inside a woman's reproductive tract, it's possible for one of those little swimmers to hang on until you ovulate, explained Dr. Kallen. Not to mention, many women's cycles aren't a perfect 28-days, so shorter periods and longer ovulations give sperm a better window to fertilize an egg.

If you want to know what your ovulation pattern is, you can track the number of days between your periods. This includes when you start your period, and then when you start your period again. After doing this for several months, you'll have a good idea of when your ovulation cycle occurs. There are multiple apps that track periods and they make the process of keeping track of your period much easier.

If you're on an effective method of birth control and take it correctly, you have an even lower chance of getting pregnant on your period because most birth control pills and other hormonal contraceptives like Depo-Provera prevent you from releasing an egg, Dr. Kallen explained. However, no birth control method is 100% effective, according to the Centers for Disease Control & Prevention. While small, there is still a chance of getting pregnant while on your period and on birth control pills.

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