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If you’re a woman, you may have heard the claim that your menstrual cycle is your “fifth vital sign.” Maybe that makes intuitive sense to you, if you’re someone who’s used to practicing a fertility awareness method to track your menstrual cycle, monitoring and recording your reproductive health through various biomarkers. But for many others, the idea of one’s period as a fifth vital sign might sound like a strange—if not downright wrong—claim. What could be so “vital” about a period, anyway, which gives many women more than their fair share of frustration and pain?

According to Johns Hopkins Medicine, “Vital signs are measurements of the body's most basic functions.” There are “four main vital signs routinely monitored by medical professionals and health care providers,” says Hopkins. These four signs are: Body temperature, pulse rate, respiration rate, and blood pressure.

In the 1990s, there was a push to recognize “pain” as a fifth vital sign to be monitored in addition to the four above. But because pain cannot be objectively measured, it was difficult to make the case for including it alongside the other four objectively measurable signs.

In more recent years, however, women’s health advocates have been using the term, “the fifth vital sign,” to refer to a woman’s menstrual cycle, and there is even an eponymous book on the subject written by Fertility Friday podcast founder Lisa Hendrickson-Jack. To use the Hopkins definition of vital sign, this characterization of the menstrual cycle means that it is one of a woman’s body’s “most basic functions.”

As a women’s health advocate myself, I have to agree.

How is your period a vital sign?

In a culture that believes periods, ovulation, and fertility are optional, it’s a tough sell. After all, pharmaceutical companies routinely run ads for birth control telling women their periods are unnecessary, general practitioners and OBGYNs prescribe these drugs as a basic standard of care for being a woman of reproductive age, and news organizations and scientific journals publish articles saying the same.

So what biological evidence is there to make the claim that the menstrual cycle is, in fact, an important biological process, let alone a vital sign?

This past year, the women’s health literacy site Natural Womanhood published a series of articles on “Reasons Women Need Periods,” where fertility awareness educator Cassondra Moriarty shared the latest research on how a woman’s cycle impacts her brain, bone, heart, and immunological development. As the article series shows, contrary to Big Pharma’s claims, there are concrete reasons why women need their menstrual cycles—especially teenage girls, as their bodies continue to grow and develop.

Specifically, women need to experience the cyclical effects of estrogen and progesterone, as their bodies undergo the monthly process of preparing to ovulate, ovulating, awaiting implantation of a fertilized egg, and menstruation if the egg is not fertilized or implanted. It is, in part, the cyclical exposure to these important endogenous (i.e., naturally occurring) hormones in the correct balance that allows for the important processes of bone density development and cervical tissue maturation, as well as maintaining the body’s proper stress response and protecting brain plasticity—just to name a few important functions these sex hormones serve in the female body on a regular basis.

As evidenced by evolution, biology, and well, the continued existence of the human race across the millennia, female fertility (which cannot exist without the menstrual cycle) is truly is one of the female body’s most basic and important functions. Therefore, physiologically speaking, the absence or aberrance of a menstrual cycle is a sign that something, biologically, is wrong.

A period problem indicates something wrong with one’s overall health

Like the other four vital signs, a woman’s menstrual is a clue to her overall health. Just as high blood pressure or a fast pulse gives clues to a person’s cardiovascular health and emotional state, the various qualities of a woman’s cycle give clues to the rest of her physical, and even mental and emotional functioning.

For example, knowing the length of time a woman has in between periods, and how much that length of time varies is—at the most basic level—how cycle “regularity” is determined. From a history of irregular periods comes the clue that ovulation—the midpoint of the cycle—is also irregular, and may not be happening frequently (or at all). The lack of healthy, regular ovulation does not occur in a vacuum; a woman experiencing irregular ovulation and periods will likely have other concerning symptoms, including: painful periods with heavy bleeding, severe acne, mood swings, and many others. These symptoms can range from mildly annoying to debilitating, causing girls and women to miss out on school, work, and other activities that contribute to general thriving.

Just as regular, healthy ovulation points to a healthy, unstressed body, symptoms of irregular ovulation points to the opposite. Often, an imbalance in the endogenous sex hormones estrogen, progesterone, and even testosterone can be the culprit. Sometimes that imbalance can point back to correctable problems with one’s diet or lifestyle; other times, it can point to deeper issues within one’s body requiring closer medical attention. Either way, the presence of an irregular and/or painful period is often the most glaringly obvious clue that something is wrong in her body that has implications far beyond her fertility.

How to resolve menstrual cycle irregularities

No matter the reason for a woman’s irregular and/or painful periods, seeking to correct the root cause often results in better health for a woman overall—which, again, underlines how vital a healthy menstrual cycle is to a woman’s body’s basic functioning. Natural Womanhood features many stories from real women who have been able to find healing for their painful periods, and they are often surprised to discover how correcting this (seemingly) singular aspect of their health has implications for other areas of their health and well-being, as well.

Unfortunately, teenagers and young women suffering from irregular periods often find themselves being auto-prescribed hormonal contraceptives as a bandaid solution, rather than being given treatment options that actually address the root cause of their menstrual cycle issues. And just as hormonal contraception doesn’t correct a woman’s irregular cycle—instead, it overrides it completely—it cannot heal or correct many of the subsequent effects of an irregular period on her health.

This is why both a woman with irregular periods and a woman on birth control are at an increased risk of developing osteoporosis later on in life; neither are receiving the necessary exposure to the cyclic effects of endogenous estrogen and progesterone that allow for proper bone density formation (and which produce a healthy menstrual cycle). In fact, one study even found a disturbing correlation between irregular cycles and premature death; if you think your irregular period isn’t telling you something about your overall health, think again.

Just as a person’s blood pressure or temperature clues us in to how well the body is performing a variety of biological processes (or whether they are performing those functions under the duress of infection, clogged arteries, and so on), the characteristics of a woman’s period clue a knowledgeable medical provider into the state of many other biological processes in her body.

Signs of a larger problem

What are some of the signs that your period is informing you of a deeper problem with one of your body’s most basic functions as a woman?

  • Your cycle (that is, the time you go between periods) is consistently shorter than 21 days or longer than 36 days
  • Your cycle length consistently varies by 5 or more days
  • You experience mid-cycle spotting or bleeding
  • You have very heavy and/or prolonged bleeding during your period
  • You experience intense pain or cramping with your periods and/or mid-cycle, with or without nausea or vomiting
  • You experience brown bleeding at the beginning or end of your period
  • You experience intense bloating leading up to and/or during your period
  • You find yourself feeling extremely emotional, anxious, or angry leading up to and/or during your period, with intense swings in mood
  • You have painful cystic acne and/or hirsutism (male pattern hair growth)

If you have ever been told that these experiences are normal, or worse, that there’s nothing that can be done for you (except for going on birth control to cover up the symptoms), know that both of those statements are false. Issues with your cycle are one of your body’s ways of letting you know that something is wrong, and a knowledgeable provider trained in restorative reproductive medicine can help you heal from the root causes of these symptoms.

Just as a good provider will seek to get to the bottom of a prolonged elevated temperature, rather than giving you a fever reducer and sending you on your way, a restorative reproductive medical provider will treat your cycle as the vital sign that it is. He or she will take your persistent, irregular and/or painful period symptoms seriously, searching for the root cause(s) and helping you heal not only your fertility, but restoring the other bodily processes that rely on the cyclical endogenous sex hormone exposure of the female cycle as well.

No matter what you’ve heard before now, today is a new day. You can start listening to what your body is telling you and take action to address any health issues that need addressing.