Can You Get Pregnant on Your Period?

A woman holding a pregnancy test

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Getting pregnant during your period is unlikely, but it is possible. Any time you have unprotected sex right before or during ovulation—your peak fertile window—there's a chance you can get pregnant. And while you're not technically fertile if you have sex during menstruation, pregnancy is still possible if you ovulate right after having a period.

How You Can Get Pregnant on Your Period

During your period, you can’t get pregnant the moment you have sex because you don’t ovulate during your period. Ovulation is the most fertile part of your menstrual cycle when your body releases an egg that sperm can fertilize. However, even if sperm can’t get to an egg immediately when you’re menstruating, sperm can live in your body for three to five days, even when you're menstruating. That means if you have unprotected sex on your period and then ovulate shortly after, you can become pregnant. 

It’s also possible to mistake other types of bleeding as your monthly period, making someone think they got pregnant on their period. While not common, some people can experience light vaginal bleeding, or spotting, during ovulation. Pregnant people can experience implantation bleeding—when a fertilized egg implants onto the uterus. This can happen about one to two weeks after ovulation when menstruation usually begins. There are also other reasons why someone may bleed at different times during their cycle, including polyps or endometriosis.

The Chances of Getting Pregnant on Your Period

Overall, your chances of getting pregnant during your period are low. However, your chances increase if you have a shorter menstrual cycle (less than 28 days) and ovulate a few days after your period. 

A 2013 study of 5,830 women found that day four of the menstrual cycle, which is usually during menstruation, had a 2% chance of being within the fertile window. However, ovulation timing varies and can occur about 10 to 21 days after your period starts. So if you ovulate close to day 10 or earlier in your menstrual cycle, sperm can stick around long enough to reach ovulation if you’ve had period sex.

If you ovulate later in your cycle (typically around day 14 for 28-day cycles), the chances of getting pregnant during your period decrease. That same study found that people who had sex on day 12 of their menstrual cycle had a 58% chance of hitting their fertile window. So if you typically ovulate anywhere from 12 to 21 days after your period starts, you have a very low risk of getting pregnant by having sex during your period. 

Understanding Your Menstrual Cycle

The menstrual cycle involves hormonal changes that prepare you for pregnancy. The average menstrual cycle lasts 28 days, with day one starting with your period and the last day ending on the day before your next period. However, people's cycle length can vary, with “regular” menstrual cycles lasting anywhere from 24 to 38 days.

People typically have their period during days one through five of their menstrual cycle. When a fertilized egg doesn’t implant—and you don’t become pregnant—your body sheds the lining of your uterus to start your period. The days before and during your period are unlikely times to become pregnant because there is no egg ready to be fertilized. 

After your period ends, estrogen levels increase to prep your body for ovulation, the time you are most likely to become pregnant. Ovulation usually happens around days 12 to 14 if you have a 28-day cycle. However, it’s normal to ovulate sooner or later.

During ovulation, one of your ovary follicles releases an egg. If this egg is fertilized by sperm within 12 to 24 hours, it then makes its way to implant in your uterus and you become pregnant. You are also more likely to get pregnant if you have sex within your fertile window—or a few days before and after ovulation.

If you don't become pregnant during ovulation, your body will decrease estrogen and progesterone levels to tell your body to prepare for your period. This process usually lasts seven to 19 days and is also one of the least likely times you can get pregnant.

How To Prevent Pregnancy

The only foolproof way to prevent pregnancy is to avoid sex. However, birth control and barrier methods can help you decrease your odds of becoming pregnant

Barrier Birth Control Options

Barrier birth control methods involve creating a physical barrier that prevents sperm from entering the vagina or cervix. Some barrier methods, like latex and polyurethane condoms, also help prevent sexually transmitted infections. Some common barrier methods include:

  • Condom: This thin sheath made of latex, polyurethane, or natural membrane is placed over the penis to prevent sperm from entering the vagina. Also called a male condom, this is the most effective barrier method (when made of latex or polyurethane) for reducing your risk of STIs. 
  • Internal condom: Also called a female condom, this thin pouch is inserted into the vagina. A thick, inner ring helps the condom stay in place at the back of the vagina, while a thin, outer ring creates an opening outside of the vagina. These condoms also provide some STI prevention. 
  • Diaphragm and cervical cap: A diaphragm looks like a shallow, dome-shaped cup made of silicone or latex, while a cervical cap can be made of plastic and resembles a thimble. Both methods are loaded with spermicide-–a sperm-killing chemical—and inserted into the vagina to cover the cervix to prevent sperm from entering. You must leave these barriers in for 6 hours after sex, and they both require a prescription. 
  • Sponge: This small, round piece of soft foam contains spermicide and is inserted inside the vagina until it covers the cervix. The spermicide helps kill sperm, while the sponge prevents sperm from entering the cervix. 

You can combine other barrier methods with male condoms to help increase pregnancy and STI prevention.

Intrauterine Device Birth Control Options

An intrauterine device (IUD) is a small, plastic T-shaped device a healthcare provider inserts into the uterus to help prevent pregnancy. IUDs can offer pregnancy prevention for years and come in both hormonal and non-hormonal types:

  • Hormonal IUD: Hormonal IUDs secrete progestin levonorgestrel. This hormone helps thicken your cervical mucus and thin the lining of your uterus to prevent fertilization and implantation. Hormonal IUDs can help prevent pregnancy for three to eight years.
  • Copper IUD: This IUD is made with copper and contains zero hormones. Instead, copper helps kill sperm like a spermicide to help prevent pregnancy. Copper IUDs can provide pregnancy prevention for up to 10 years.

Hormonal Birth Control Options

Additional birth control methods use hormones like estrogen and progestin to help prevent pregnancy. These hormones can stop the ovaries from releasing eggs during ovulation, thicken cervical mucus to stop sperm, or thin the uterine lining to avoid implantation. Birth control options that use one or both of these hormones include:

  • Birth control pill: Birth control pills release hormones to help prevent pregnancy when taken orally. Combined pills contain estrogen and progestin, while mini-pills (or progestin-only pills) only contain progestin to help prevent pregnancy. 
  • Birth control patch: A thin patch is placed on the back, upper arm, buttocks, or lower abdomen and releases progestin and estrogen into your body. One patch is used weekly for three weeks, and then you do not wear a patch on the fourth week to have a period. 
  • Vaginal ring: A flexible, plastic ring is inserted into the vagina and releases progestin and estrogen to help prevent pregnancy. Rings stay inside the vagina for three weeks and are taken out for a week to have a period. 
  • Contraceptive shot: This injection contains progestin to help prevent pregnancy. It is administered by a healthcare provider into the arm or buttocks every three months.  
  • Implant: A thin rod is inserted under the skin of the upper arm. It releases progestin into the body for about 3 years to help prevent pregnancy.

Other Ways to Prevent Pregnancy

The only 100% way to prevent pregnancy is abstinence. However, there are other ways to help prevent pregnancy without barrier methods or birth control, including:

  • Natural family planning (fertility awareness) method: You can track your menstrual cycle and estimate when you’ll ovulate. This typically involves a mix of calendar tracking and monitoring basal body temperature changes, cervical fluid changes, and positive ovulation tests. That way, you can avoid sex during your fertile window or use barrier methods.
  • Withdrawal: Also called the pull-out method, withdrawal involves the partner with a penis pulling out of the vagina before they ejaculate. This prevents sperm from entering the vagina, but there is a chance sperm is released during withdrawal.

Keep in mind, these methods do have high failure rates. If you had sex and are worried you may become pregnant, you can also take emergency contraception (EC). EC can help prevent pregnancy three to five days after having unprotected sex by delaying ovulation or changing the uterus lining to avoid implantation. The FDA currently approves two types of EC pills: over-the-counter levonorgestrel pills and prescription ulipristal acetate pills. A copper IUD can also be inserted by a healthcare provider as a form of EC.

A Quick Review

The odds of getting pregnant during your period are very low. Still, it is possible that having sex on your period can lead to pregnancy because sperm can live in your body for three to five days. People with menstrual cycles under 28 days can ovulate right after their period, which increases their risk of getting pregnant on their period because sperm can wait around until ovulation.

There is always a risk of pregnancy when you have sex, especially unprotected sex. But if you don't want to get pregnant right now, barrier methods like condoms and birth control methods can help you prevent pregnancy. 

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