Can You Get Pregnant On Your Period?

Though the chances are slim, it's possible to get pregnant by having unprotected sex on your period. Here's what you need to know.

Think you don't need to use protection if you have sex on your period? As it turns out, that's not entirely true. "It's technically possible to get pregnant while on your period, but it's rare for this to happen," says Barbara Stegmann, M.D., a triple board-certified OB-GYN and women's health clinical lead at Organon. Keep reading to learn why it's possible to conceive by having penis-in-vagina (PIV) sex during menstruation.

How Does Conception Occur?

To learn why it's possible to get pregnant on your period, it helps to understand the menstrual cycle. Every month, a person releases a mature egg from their ovaries, which is known as ovulation. This usually happens around day 14 of your cycle (day one is the first day of your period), but the timeline varies for everyone.

After the egg is released, it travels down the fallopian tube, where it awaits fertilization with sperm. Sperm can survive for several days in the reproductive tract, so a person can get pregnant by having sex during ovulation or the days leading up to it, explains Michele Hakakha, M.D., a board-certified obstetrician and gynecologist based in Los Angeles and co-author of Expecting 411: Clear Answers and Smart Advice for Your Pregnancy.

"Prior to the release of the egg, the hormones in a woman's body increase to prepare (and thicken) the lining of the uterus in case the egg is fertilized and a pregnancy occurs," says Dr. Hakakha. "If there's no fertilization, the lining of the uterus is sloughed off about 14 days later. This is called your period."

In other words, a period is the blood loss that happens at the end of an ovulatory cycle, as the result of an egg not being fertilized by sperm. Most people have periods that last from two days to eight days and take place every 26 to 34 days.

woman holding a positive pregnancy test

Getty Images / ArtistGNDphotography

Is It Possible to Get Pregnant on Your Period?

You can only get pregnant by having sex during ovulation or the days leading up to it. Most people have menstrual cycles that last 26 to 34 days, and if someone with this cycle has an average two- to eight-day menstrual period, they will probably not get pregnant during their period. An egg that's released during ovulation but remains unfertilized "comes out with all of the menstrual blood," explains Dr. Hakakha.

That said, the chance of pregnancy on your period increases if you have an irregular cycle. A person with a shorter menstrual cycle (24 days, for example), could have seven days of bleeding, have intercourse on their final day of bleeding, and ovulate three days later, says Dr. Hakakha. "Since sperm live for three to five days, she could definitely get pregnant" if it fertilizes a released egg, which has a lifespan of about 24 hours.

In addition, some people experience breakthrough spotting or bleeding between periods. This can occur near ovulation and be mistaken for a period, making it difficult to establish your exact place in the menstrual cycle. Having sex during ovulation increases your chances of getting pregnant.

Chances of Getting Pregnant on Your Period

You're unlikely to conceive by having sex on your period, but it can happen. Consider the results of a 2013 study, which analyzed conception probabilities from 5,830 people. The study found that chance of conception rises seven days after your last menstrual period, and it peaks at 15 days. That said, researchers found a 2% probability of "being within the fertile window" at day four—and many people are still on their period during that time.

These factors increase the odds of getting pregnant on your period:

  • Irregular periods
  • Short menstrual cycles
  • Spotting or mid-cycle bleeding that's mistaken for a period
  • Period bleeding that lasts a long time, carrying over into your fertile window

Can You Get Pregnant Right After Your Period?

After menstruation, you're moving closer to the fertile window each day. It's possible to get pregnant right after your period if you ovulate around that time.

The American Pregnancy Association says that during a typical cycle (28 to 30 days), the fertile window is usually between days 11 and 21, but this varies widely between people. Those with shorter menstrual cycles might enter their fertile window around day 8 or 9, for example, which could be right after their period ends.

Again, the possibility of conception is greater is you have short menstrual cycles, you've miscounted cycle days, or your period bleeding lasts a long time.

Can You Get Pregnant Right Before Your Period?

There's a low chance of conception by having sex right before your period. After an egg is released during ovulation—which usually happens midway through your cycle—it only survives for 12 to 24 hours in the reproductive tract. If it's not fertilized during this time, it can't form a pregnancy. You'll need to wait until your next fertile window to conceive again.

Of course, there's no guarantee when having unprotected sex, so you'll still want to be diligent about birth control if you're not trying to conceive. This is especially true for people with irregular cycles, who might ovulate closer to their menstrual cycle's start date.

The Bottom Line

"Unprotected intercourse can result in pregnancy if the sperm and egg can get together and you are off in your timing estimates," says Lauren Sundheimer, M.D., MS, FACOG, an OB-GYN practicing in Orange County, California. "If you are able to track your fertile window, then having intercourse outside of when you are considered fertile or when you are nearing ovulation might be safe, but there is never a guarantee that you will not get pregnant."

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  1. Day-specific probabilities of conception in fertile cycles resulting in spontaneous pregnancies. Hum Reprod. 2013.

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