Ever noticed your period messes with your bowel movements? Here's why.

Image: So, we meet again… (via iStock).

Periods. They’re great fun, no? There’s the bloating, the acne, the clumsiness, the mood swings, the memory lapses… and for many of us, there can also be a noticeable change in digestion.

Some women experience overly rumbly tummies, others diarrhoea. Either way, the question remains: why do our bowel movements go funny around our periods?

You can place some of the blame on your prostaglandins — these are chemicals which regulate the female reproductive system and are involved in the control of ovulation and the menstrual cycle.

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“They are released when you have your period. When you get a surge of estrogen during your period, you also get prostaglandins. You need them to keep everything in check,” explains Dr Sara Baqar, an endocrinologist based in Melbourne.

Prostaglandins, especially if present in excess, can result in the uterine cramping and discomfort many women experience during their menstrual period. (Post continues after gallery.)

“The body produces prostaglandins which make the muscle of the uterus contract at period time to help expel the lining which gives the bleeding each month,” Dr Ruth Hand, a Melbourne-based GP explains.

However, that’s not the only side-effect they can contribute to.

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“The prostaglandins can also work on the muscle cells in the bowel, making them contract as well as giving diarrhoea. They can also cause headaches and nausea and vomiting,” Dr Hand adds.

Prostaglandins are one of the most common causes for bowel discomfort during your period. One UCLA study study found women who experience diarrhoea while menstruating have higher levels of the chemical.

Now the primary culprit has been identified, are there any ways to reduce the effect of prostaglandins on our digestive systems?

"Anti-inflammatory drugs such as Nurofen and aspirin can block the prostaglandins working, so they are useful for period pain," Dr Hand says.

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"They are taken in the first few days of the period, but some people have more benefit if they start them one to three days before the period is expected. Prostaglandin is the drug often given to pregnant women to make the uterus contract to bring on labour."

There are other, less common causes for extreme changes in your digestion during your period. These include conditions Endometriosis, pelvic inflammatory disease, irritable bowel syndrome and dysmenorrhoea, so it's best to consult your doctor if you do experience disruptive changes when you get your period — for instance, if your symptoms are extreme or you are experiencing significant pain or bloody stools.

How is your body affected by your period?