Ovulation happens when your ovary releases a mature egg and sends it down your fallopian tube, where it can be fertilized by sperm. This typically happens in the middle of your menstrual cycle—for example, on day 14 of a 28-day cycle. But everyone is different, so pinpointing this precise window (your egg only hangs out in the fallopian tubes for 12 to 24 hours) can be a little tricky.

While you can certainly rely on ovulation tracking kits and apps to figure out when you’re in this window, your body may also give you clues about when you’re ovulating—one of these being your bathroom habits.

“Because the GI tract and the reproductive system share the pelvis, often something that affects one may affect the other,” says Allison K. Rodgers, MD, a board-certified OB/GYN, reproductive endocrinologist, and director of education at the Fertility Centers of Illinois.

That means during different times in your menstrual cycle, your bowels may become a bit backed up or flow more freely. In fact, many people notice watery poop or even diarrhea during ovulation. Here, learn more about why digestive issues during your fertility window happen, and other signs of ovulation to look out for.

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Is diarrhea a sign of ovulation?

The short answer: It can be. “Some people notice a huge correlation between their menstrual cycles and bowel symptoms,” says Dr. Rodgers. For many, that means diarrhea during certain phases in their cycle—including ovulation.

Hormone-like substances called prostaglandins are to blame for these bowel issues. Prostaglandins play a role in smooth muscle contractions in your reproductive organs, says Dr. Rodgers. But they also relax your intestinal muscles. So when your body releases them during ovulation, “the smooth muscle of the GI tract responds by moving digested food through faster,” she says. The result? Occasional diarrhea.

Another time you might have diarrhea during your menstrual cycle is right before or during your period. “The uterus creates prostaglandins as it’s contracting to release menstrual fluid,” says Dr. Rodgers. This can cause more frequent or runny bowel movements, also known as period poops.

But keep in mind that everyone’s different. “Other people aren’t sensitive to [prostaglandins] at all, and don’t see any changes in bowel function during ovulation or periods,” says Dr. Rodgers. Or if you already deal with a GI issue that causes diarrhea (like IBS, for example), it may be hard to tell whether watery stools are from ovulation or your condition. In other words, diarrhea is not always the most reliable sign you’re ovulating.

What conditions can increase your chances of diarrhea during ovulation?

While many of us get the period poops, certain people are more prone to digestive issues like diarrhea during their menstrual cycle. For example, people with existing health issues like endometriosis may have more intense diarrhea around ovulation time, says Dr. Rodgers. Endometriosis is a condition where tissue similar to the lining of the uterus grows outside of the uterus. If you have endometriosis on the bowel itself (called bowel endometriosis), it may cause diarrhea or looser stools, she adds.

Similarly, people with chronic digestive issues like irritable bowel syndrome (IBS) and Crohn’s disease may have more severe digestive woes during their period, according to the Cleveland Clinic.

And sometimes, even things like stress can heighten your chances of period poops or period flu (i.e., when you feel flu-like symptoms during your period).

Other signs of ovulation

Because every person with a uterus is different, you may or may not have symptoms during ovulation. That said, some of the most common signs of ovulation include the following, per the Cleveland Clinic:

• A slight increase (about 0.5 to 1 degree) in basal body temperature (i.e., your temperature when you’re fully at rest)
• A change in cervical mucus (just before ovulation it turns clear and slippery like egg whites)
• Tender breasts
• Bloating
• Minor pelvic or abdominal pain (often in the middle or on one side, known as mittelschmerz)
• Light bleeding or spotting
• Changes in the position and firmness of your cervix (i.e., the small canal that connects your uterus and vagina)
• Increased sex drive
• Heightened sense of smell, taste, or sight
• Mood changes
• Appetite changes

If you’re trying to get pregnant (or avoid pregnancy if you’re not on hormonal birth control), looking out for these symptoms can help you figure out whether you’re ovulating. Over time, you’ll get used to noticing these signs and symptoms, which could help you anticipate when you’ll start ovulating.

When to see a doctor

Hormonal fluctuations and diarrhea often go hand in hand. In most cases, diarrhea during ovulation (or menses) is totally normal. “It’s common and physiologic,” says Dr. Rodgers. But if diarrhea becomes severe or excessive, make an appointment with your doctor. Same goes if you have diarrhea along with these other symptoms:

• Intense pelvic pain
• Cramping (including pelvic, back, or anus cramps)
• Blood in your stool

Your doctor can help rule out any underlying health conditions or infections that cause diarrhea.

FAQ

Can endometriosis flare up during ovulation?

Unfortunately, yes. Endometrial tissue is sensitive to hormonal changes, so it can become irritated during different points in your menstrual cycle, according to the Cleveland Clinic. And ovulation—which involves the release of prostaglandins—is one of those times, says Dr. Rodgers.

On top of this, endometriosis can damage nerves in your pelvis, making them even more sensitive to pain sensation, she adds. So, while mild cramping and pelvic discomfort are common (and normal) during ovulation, people with endometriosis are more likely to have these symptoms with greater intensity.

If your endometriosis flares are affecting your quality of life, talk to your doctor about treatment options like hormonal birth control. Certain “birth control pills—which lighten flow, decrease prostaglandins, and prevent ovulation—can decrease the symptoms of endometriosis,” says Dr. Rodgers.

What hormone causes diarrhea during ovulation?

“Mainly prostaglandins,” says Dr. Rodgers. But a buildup of progesterone can lead to loose stools, too. This period-related hormone, which thickens the walls of your uterus, spikes right before ovulation, per the Cleveland Clinic.

While it’s actually more common for people to get constipation from progesterone, it may cause diarrhea for others. This really just depends on the person. We’re all unique, so the way our bodies (and bowels) respond to hormones will be unique, too.

Can diarrhea be a sign of fertilization during ovulation?

Not necessarily. Typically, there aren’t any symptoms that indicate an egg has been fertilized by a sperm. That said, you may have mild GI symptoms, including diarrhea or nausea, during or after implantation—i.e., once the fertilized egg has been implanted into the wall of your uterus. Implantation may also cause light vaginal spotting or bleeding, per the Cleveland Clinic, though this doesn’t always happen to everyone. If you think you may be pregnant, you can take an at-home pregnancy test or call your doctor to get a urine test at their office.

—medically reviewed by Andrea Braden, MD, OB/GYN