Getting pregnant during your period is unlikely, but it is possible. Anytime you have unprotected sex right before or during ovulation — your fertile window — there’s a chance you’ll get pregnant. And while you’re not technically fertile if you have sex during your period, pregnancy is still possible if you ovulate right after a period.
During your period, you cannot get pregnant the moment you have sex because you do not ovulate during your period. Ovulation is the most fertile part of your menstrual cycle when your body releases an egg that can fertilize sperm. But even if sperm can’t get to an egg right away when you menstruate, sperm can stay in your body for three to five days even if you menstruate. That means if you have unprotected sex during your period and ovulate soon after, you can get pregnant.
It’s also possible to confuse other types of bleeding with your monthly period, causing one to become think they became pregnant during their period. Although uncommon, some people may experience light vaginal bleeding or spotting during ovulation. Pregnant people can experience implantation bleeding, when a fertilized egg implants in 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.
In general, 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, usually during menstruation, had a 2% chance of being within the fertile window. However, the time of ovulation varies and can occur about 10 to 21 days after the start of your period. So if you ovulate around day 10 or earlier in your menstrual cycle, sperm can hang around long enough to reach ovulation if you’ve had period sex.
If you ovulate later in your cycle (usually 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 reaching their fertile window. So if you normally ovulate anywhere from 12 to 21 days after the start of your period, you have a very low risk of getting pregnant by having sex during your period.
The menstrual cycle involves hormonal changes that prepare you for pregnancy. The average menstrual cycle lasts 28 days, with the first day starting with your period and the last day ending the day before your next period. However, people’s cycle lengths can vary, with “normal” menstrual cycles lasting between 24 and 38 days.
People usually have their period during days one through five of their menstrual cycle. When a fertilized egg doesn’t implant — and you don’t get pregnant — your body sheds the lining of your uterus to start your period. The days before and during your period are unlikely times to get pregnant because no egg is ready to be fertilized.
After your period is over, estrogen levels increase to prepare your body for ovulation, the time when you are most likely to conceive. Ovulation usually occurs around day 12 to 14 if you have a 28 day cycle. However, it is normal to ovulate sooner or later.
During ovulation, one of your ovarian follicles releases an egg. If this egg is fertilized by sperm within 12 to 24 hours, it will find its way to implantation in your uterus and you will 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 get pregnant during ovulation, your body will lower estrogen and progesterone levels to tell your body to prepare for your period. This process usually takes seven to 19 days and is also one of the least likely times you can get pregnant.
The only surefire way to avoid pregnancy is to avoid sex. However, birth control and barrier methods can help reduce your chances of getting 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, such as latex and polyurethane condoms, also help prevent sexually transmitted infections. Some commonly used barrier methods are:
- Condom: This thin latex, polyurethane, or natural membrane sheath is placed over the penis to prevent sperm from entering the vagina. Also known as a male condom, this is the most effective barrier method (when made of latex or polyurethane) to reduce the risk of STIs.
- Internal condom: This thin pouch, also called a female condom, 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 the vagina. These condoms also offer some STD prevention.
- Diaphragm and neck cap: A diaphragm looks like a shallow, dome-shaped cup made of silicone or latex, while a cervical cap can be 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 have to leave these barriers on for 6 hours after sex and they both require a prescription.
- Sponge: This small, round piece of soft foam contains spermicide and is inserted into 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 increase pregnancy and STI prevention.
Intrauterine contraceptive options
An intrauterine device (IUD) is a small, plastic T-shaped device that a healthcare provider inserts into the uterus to help prevent pregnancy. IUDs can provide years of pregnancy prevention and come in both hormonal and non-hormonal types:
- Hormonal IUD: Hormonal IUDs secrete the 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 as a spermicide to help prevent pregnancy. Copper IUDs can prevent pregnancy for up to 10 years.
Hormonal birth control options
Additional birth control methods use hormones such as estrogen and progestin to help prevent pregnancy. These hormones can stop the ovaries from releasing eggs during ovulation, they can thicken the cervical mucus to hold back sperm, or they can thin the uterine lining to prevent 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. Combination pills contain estrogen and progestin, while minipills (or progestin-only pills) contain only progestin to help prevent pregnancy.
- Contraceptive 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 don’t wear a patch in the fourth week to get your period.
- vaginal ring: A flexible, plastic ring is inserted into the vagina and releases progestin and estrogen to help prevent pregnancy. Rings remain in the vagina for three weeks and are removed for one week to get your period.
- Contraceptive injection: This injection contains progestogen to help prevent pregnancy. It is administered into the arm or buttocks every three months by a healthcare provider.
- 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.
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 ovulate. This usually includes a combination of keeping a calendar and monitoring changes in basal body temperature, changes in cervical fluid, and positive ovulation tests. That way you can avoid sex during your fertile window or use barrier methods.
- Intake: Also called the pull-out method, withdrawal involves the partner pulling out of the vagina with a penis before they ejaculate. This prevents sperm from entering the vagina, but there is a chance of sperm being released during extraction.
Keep in mind that these methods have high failure rates. If you have had sex and are concerned that you could become pregnant, you can also use emergency contraception (EC). EC can help prevent pregnancy three to five days after unprotected sex by delaying ovulation or changing the uterine lining to prevent 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.
The chance of getting pregnant during your period is very small. Still, it’s possible that having sex during your period could lead to pregnancy, as sperm can live in your body for three to five days. People with menstrual cycles less than 28 days may ovulate right after their period, which increases their risk of getting pregnant during their period because sperm can wait until ovulation.
There is always a risk of pregnancy if 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 avoid pregnancy.