Can You Get Pregnant on Your Period?
June 29, 2021
Can you get pregnant on your period? It’s a common question women ask, whether they’re hoping to have a baby or trying to avoid pregnancy altogether. The answer can be tricky, given how confusing the timing of ovulation can be. That said, we reached out to experts to find out once and for all whether getting pregnant on your period—or directly before or after it—is even a possibility, and how to figure out when you’re least and most fertile.
Before we dive into whether you can get pregnant on your period, let’s first talk about ovulation, since understanding how your cycle works is key here—and regardless of whether you’re trying to conceive or avoid pregnancy, timing when you have sex is a critical piece of the puzzle.
Ovulation refers to the midpoint phase of your menstrual cycle when the ovary releases a mature egg. The average length of a cycle—from the first day of your period to the first day of your next period—is 28 days, but that varies greatly from person to person. In fact, cycles that last anywhere from 24 to 35 days are considered normal, says Jaime Knopman, MD, a fertility specialist in New York City.
Most women regularly ovulate each month, sometime between day 12 and 21 of their cycle, but the precise day that ovulation takes place can vary from person to person. (Despite the longstanding myth, not every woman ovulates on day 14 of their cycle!) What’s more, according to the American Pregnancy Association, your ovulation timing can differ month to month. Several factors can contribute to irregular timing, such as stress, obesity, illness, smoking and drastic changes to your sleep or work schedule.
After the egg is released, it moves on to the fallopian tube, where it typically survives for 12 to 24 hours. There, it can meet up with any available sperm, which can usually live in a woman’s body for about three days and sometimes as long as five. That’s why the five days leading up to ovulation, and the day of, are when women are most fertile.
While the timing of ovulation can be sporadic, what fluctuates less is when menstruation kicks in. Healthy women get their periods 12 to 14 days after ovulation if the egg isn’t fertilized, Knopman says, and bleed for four to five days on average.
Now that you better understand your menstrual cycle, ovulation and your fertile window, we can get down to the question at hand: Can you get pregnant on your period? Answer: While extremely unlikely, it is technically possible, under rare circumstances. Several factors determine whether you can get pregnant on your period, including the length of your menstrual cycle, when you ovulate and the amount of time the sperm survive.
So why is getting pregnant on your period so unlikely? It’s all a matter of simple math. Depending on when during your period you have sex, you’ll likely have at least seven days, if not more, before you ovulate. The sperm isn’t likely to survive that long, which is why “a woman with a regular menstrual cycle will not get pregnant on her period,” says Fahimeh Sasan, DO, founding ob-gyn of Kindbody, a fertility and family-building clinic in New York City.
But here’s the snag: If you happen to have very long periods (i.e., more than seven days long) and very short menstrual cycles, then you could get pregnant if that bleeding happens to take place during the time of your ovulation. “If you have a 21-day cycle, you’d likely ovulate around day seven. And if you’re still on your period by day seven, it may be possible to get pregnant,” says Megan Cheney, MD, MPH, medical director at the Women’s Institute at Banner-University Medical Center in Phoenix, Arizona.
While the chances of getting pregnant on your period for most women with regular cycles are extremely low, this isn’t necessarily the case if you’re bleeding for other reasons. Some women have episodes of spotting between their periods and even bleed (lightly) during ovulation. They may assume they’re on their period, when in fact it’s their most fertile time of the month. That’s why it’s important for every woman to know her own unique menstrual patterns, Sasan says, and why, for women with irregular menstrual cycles, it’s especially important to use contraception if they’re not actively trying to conceive. (One useful clue: The blood you see during ovulation will either be light pink or brown, rather than the dark red of your period.)
When are the odds of getting pregnant the highest?
Bottom line: It’s very hard to get pregnant on your period—nearly impossible. So when can you get pregnant? Your best bet is leading up to and during ovulation. Since the egg is viable for only 12 to 24 hours after ovulation, it has to be fertilized by sperm before that time is up. Remember, sperm can live in your body for up to five days (though three days is more common), so it’s possible to have sex before you ovulate and still conceive a few days later. On average, a woman is fertile for the five days leading up to ovulation and up to 24 hours after. So if you wait 36 to 48 hours after ovulation to have sex, you’ll be beyond your window of fertility.
Keep in mind, it’s not unusual to take several tries before you become pregnant. Often, both egg and sperm are available, but fertilization just doesn’t happen. According to one study on women with the mean age of 29, the odds of getting pregnant within the first month of properly timed sex was 38 percent, but that figure shot up to 68 percent after three months and 92 percent after a year.
So it’s way harder to get pregnant on your period than when you’re not—but can you get pregnant right after your period? It depends on what you mean by “right after.” If you mean no more than one day after your period ends, then “in most cases, no,” Knopman says. The only exception? “If you have a very short cycle and long bleeding periods,” she says. In that case, if you bleed until day seven, have sex on day eight and ovulate on day nine or 10, it’s definitely possible to become pregnant.
For women with normal cycles, though, the chances of getting pregnant start to increase only as you get closer and closer to your window of fertility. Again, most women ovulate between day 12 and day 21 of their cycles—so if you have sex just two days after your period ends, say on day seven, you’re only five days away from ovulation. So if you happen to have robust specimens of sperm swimming around—the ones that last as long as five days—there’s a chance you could get pregnant.
So what about your chances of conception just before you menstruate? Can you get pregnant the day before your period? The closer you are to your period when you have sex, the less likely it is that you’ll get pregnant. That’s because it puts you further away from the time of ovulation, and, as we mentioned, the egg lasts for only a day at most. The number of “safe days” right before your period will increase with longer cycles and decrease with shorter cycles. For women with a regular cycle, having unprotected sex the day before your period is extremely unlikely to result in a pregnancy—“almost zero chance,” Sasan says.
Getting pregnant on (or around) your period is rare, but it’s not impossible, given the right circumstances. Whether you’re in family planning mode or trying to avoid getting pregnant, it’s important to understand the timing of your individual cycle and track your ovulation—either with menstrual charting, an ovulation predictor kit or checking your basal body temperature—to help you make informed decisions about when to have sex.
Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.
About the experts:
Jaime Knopman, MD, is a board-certified reproductive endocrinologist and serves as the director of fertility preservation for CCRM Fertility in New York City. She received her medical degree from Mount Sinai School of Medicine.
Fahimeh Sasan, DO, is the founding ob-gyn of Kindbody, a fertility and family-building clinic in New York City. She completed her doctorate of osteopathic medicine at the University of North Texas in 2006.
Megan Cheney, MD, MPH, is the medical director at the Women’s Institute at Banner-University Medical Center in Phoenix, Arizona. She received her medical degree from the University of Arizona College of Medicine in 2009.
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