Periods are typically not a great experience in general, but add in the additional insult of gastric distress, and it’s a whole new level of discomfort. It turns out there is a physiological reason your period jacks up your gut, and it has to do with—you guessed it—hormones.

Your Hormones and Your Bowels

For starters, let’s take a look at your menstrual cycle, which starts on day one of your period and ends the day before your next period begins. This delicate dance is brought to you by various hormones that are produced in assorted body parts: your hypothalamus and pituitary (both located in your brain) and your ovaries. The hormones involved include progesterone, estrogen and testosterone (yes, really) that impact the timing of ovulation and in the case of no fertilization menstruation.

Progesterone production specifically increases in the latter half of your menstrual cycle (in other words, around two weeks before your period starts) and drops off right before your period begins. The whole idea is that progesterone helps your body ready itself for a fertilized egg, and when it doesn’t happen, the drop in this hormone helps signal the start of your period.

In some cases, this can mean you’re already having pooping issues well before your period starts according to Dr. G. Thomas Ruiz, an OB-GYN at MemorialCare Orange Coast Medical Center in Fountain Valley, California. “The hormones of the menstrual cycle, specifically progesterone, are thought to be associated with constipation,” he tells SheKnows. “Progesterone causes slowing of intestinal motility, which causes constipation.”

MORE: How to Eat, Sleep, and Exercise Better Every Day of the Month

Period Poops are a Thing

So, before you start spotting on cycle-day one, you may already be having some issues getting things going in the poop department. However, you may soon have a different sort of problem, and this is not always a super-fun thing. Affectionately known as the “period poops,” some of us are lucky enough to have frequent bowel movements (or, worse yet, rampant diarrhea) while we’re also bleeding from the vagina (this is not a fun combo, BTW).

Dr. Sheryl A. Ross, an OB-GYN, tells SheKnows this type of gastrointestinal havoc is not uncommon during our menstrual cycle, particularly during the first three days of our period. The culprit is prostaglandins, which are chemicals released during menses. Prostaglandins are not only responsible for menstrual cramping, but they can also (unfortunately) affect your bowels, relaxing them and causing diarrhea.

There are other ways your period can affect your bowels as well. For those who have endometriosis, bowel movements can be terribly painful (even excruciating) in those who have endometriosis implants on the large bowel. Also, Dr. Mark Trolice, a reproductive endocrinology and infertility specialist at Fertility CARE—The IVF Center and associate professor of OB-GYN at the University of Central Florida College of Medicine, tells SheKnows that people who have irritable bowel syndrome or inflammatory bowel disease can note an increase of their symptoms during menses.

MORE: 7 of the Most Common Period Symptoms, and 7 Easy, Expert Fixes

Can This Stop Being a Thing?

Since this gastric disaster is caused by natural fluctuations in your body’s hormones, is there anything you can even do to make your bowels happy? Maybe, says Ross. She suggests eating a healthy, fiber-rich and colorful diet; exercising regularly; and avoiding caffeine, sugar, salt, dairy, spicy foods and alcohol. She also recommends taking a probiotic to help balance out your gut biome, which can help improve any gastrointestinal symptoms.

So, yes, your digestive system is naturally affected by your menstrual cycle, but rest assured it’s not abnormal and you’re definitely not alone. But as always, consult a physician if you have symptoms that worry you, and don’t forget the fiber.

Originally posted on SheKnows.