Can You Get Pregnant if You Have Sex on Your Period?

Medically reviewed by Janine Kelbach, RNC-OB on March 7, 2016Written by Rachel Nall, RN, BSN, CCRN on March 7, 2016

If you’re trying to get pregnant (or trying not to get pregnant), tracking your cycle is important. It will help you keep track of the most fertile days when you can more easily conceive.

A common fertility myth is that a woman can’t get pregnant when she’s on her period. While the odds for pregnancy are lower on the days you’re on your period, they aren’t zero.

Here’s what you need to know about fertility and having sex on your period.

How Does Conception Occur?

The ability to conceive is miraculous. It requires the meeting of a male’s sperm with a female’s egg. Once a woman’s ovary releases an egg, the egg lives for only between 12 and 24 hours. The male sperm can live for about three days.

The typical female cycle is 28 days. Day 1 is when she starts her period. A woman typically ovulates around day 14 (but it could be around days 12, 13, or 14).

Ovulation is when a woman’s ovary releases an egg for fertilization. If a sperm is available in the uterus, pregnancy can occur.

Ovulation can vary based on a woman’s cycle. Some women have a longer cycle of around 35 days between periods. Ovulation would then happen around day 21. Women with a shorter cycle of 21 days ovulate around day 7.

How Can a Woman Get Pregnant on Her Period?

It’s easy to mistake vaginal bleeding for the beginning of a period. It’s possible you could bleed during ovulation when you’re most fertile. This could easily be mistaken for a period. Having unprotected sex at this time dramatically increases your chances of becoming pregnant.

For the average woman, the ovulation cycle is somewhere between 28 and 30 days. This means that if you have sex while on your period, you won’t likely ovulate until several days later. But women with a shorter cycle wouldn’t have the same amount of time between having their periods and ovulating.

Another consideration is that a man’s sperm can live inside a woman for up to 72 hours after ejaculation. Toward the end of your period, your chances of becoming pregnant will increase.

If you’re curious about your ovulation patterns, 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. Over several months, you can identify a pattern to determine roughly when your ovulation cycle occurs.

What Are the Chances a Woman Can Get Pregnant on Her Period?

A woman’s likelihood of getting pregnant can rise and fall throughout her ovulation cycle. While the average female’s monthly cycle may be 29 days, others may have a cycle that varies from 20 to 40 days, or longer.

The likelihood that a woman will get pregnant one to two days after she starts bleeding is nearly zero. But the likelihood starts to increase again with each successive day, even though she’s still bleeding. At roughly day 13 after starting her period, her chance of pregnancy is an estimated 9 percent.

While these numbers may be low, it doesn’t mean a woman can ever be 100 percent assured that she won’t get pregnant on her period.

Birth Control Precautions

If you’re trying to get pregnant, having sex on your period won’t likely help you to conceive unless your menstrual cycle is less than 28 days. But it’s always possible that you could become pregnant.

If you’re not trying to become pregnant, it’s important to have protected sex every time. This includes using some form of contraception like wearing a condom or taking birth control pills.

Birth control pills will not provide a barrier against sexually transmitted diseases like herpes, gonorrhea, or chlamydia. To protect yourself from unwanted infections, have your partner wear a condom.

The Takeaway

A woman’s ovulation cycles can vary, so it’s statistically possible you could become pregnant while on your period. While pregnancy is less likely in the earlier days of your period, the chances increase in the later days.

If you’re trying to become pregnant and haven’t conceived after a year or more of having unprotected sex, contact your doctor. They can recommend methods of tracking your ovulation, as well as fertility experts. They can provide testing and treatments that will help you increase your chances of conception. 

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