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I read this book when it first came out in January 2019 and I can honestly say it has been one of the most influential books I have ever read. It totally changed my life and I have spent a lot of time and effort telling all my friends and family about it ever since. 

The premise of the book is that the menstrual cycle is a vital sign – like pulse, temperature, respiratory rate, and blood pressure – and as such, it tells you a lot about your health. So many women know nothing more than the fact that they bleed on a regular basis and it has to do with making babies. 

There is so much more to it! And it is so important to know. Every woman who has a period or who knows someone who has a period would definitely benefit from reading this book.

With so much crucial information, there is no way I can share it all. This book review will give you a little taste of what is to come and then I beg you to please get it and read it yourself! It is so good!

Let’s begin.

Why should I care about the details of the menstrual cycle?

The menstrual cycle can tell you so much about your overall health. If you know what is normal, you can easily tell what is not. And when you can tell something is not normal, you can find the support your body needs to get you back on track.

For example, did you know that ovulation (release of an egg) is a necessary part of hormone production for women? If you’re not ovulating, you’re not producing progesterone. But why should you care about that? In addition to the role it plays in supporting a pregnancy, progesterone prevents breast cancer, boosts thyroid hormone, reduces inflammation, builds muscles, promotes sleep, protects against heart disease, and calms the nervous system. Pretty amazing, right? But if you don’t know the signs of ovulation, how would you know whether you are or not? 

Ovulation is, of course, crucial for getting pregnant. If you don’t ovulate, you don’t have an egg available to be fertilized. At the same time, if you do ovulate, you have the capacity to get pregnant, whether or not you want to. Wouldn’t it be handy to know if/when you ovulate every single month so you can prevent or optimize your chances of getting pregnant?

In short, being familiar with how the menstrual cycle works allows you to prevent pregnancy naturally, optimize your chance for pregnancy, monitor your health, and enjoy the health benefits of ovulation.

What does a normal period look like?

The menstrual cycle starts with menstruation, a.k.a. a period. A normal period is 3-7 days long, with about 25 – 80 mL of blood lost. Excessively heavy bleeding or extremely light bleeding are not normal, and neither is excessive pain or PMS symptoms. 

If you don’t use a menstrual cup, it might be hard to know how much blood you are losing. For reference, a light/regular tampon or pad holds 3-4 mL fully soaked. A medium/heavy pad or tampon holds about 8 mL when fully soaked. And a super pad or tampon holds about 12 mL when fully soaked, or about 2 tsp. 

It is important to understand that a true period only happens (about two weeks) after ovulation. If you are on a hormonal contraceptive, your “periods” are just blood for the sake of bleeding on a regular basis like everyone else… more on that in the pill section.

What does a normal menstrual cycle look like?

First of all, let’s be clear that a menstrual cycle is the entire hormone cycle, beginning with menstruation, ovulation about half way through, and then a drop in hormones at the end triggering another period and the start of a new cycle. I hear people calling their period their “cycle” and that is just the beginning…

A menstrual cycle is split into two phases. The follicular phase begins with a 3-7 day period and ends with ovulation. It varies in length from cycle to cycle, depending on things like stress levels, travel, illness, etc. Normal length could be anywhere from 10-23 days, with average being 15 days. During this phase, estrogen is high, causing the lining in the uterus to grow, and stimulating the production of cervical mucus.

I could talk for days about cervical mucus. There is an entire chapter in the book dedicated to it. It is fascinating stuff! But here’s the short version: For a few days leading up to ovulation, the body produces mucus in the cervix to keep the sperm alive until the glorious day that an egg is released. You may notice a slippery feeling when you wipe or see white or clear stuff on your underwear for a few days. This is all normal and a good sign that ovulation is approaching. 

Once the follicle is primed and ready, luteinizing hormone spikes, triggering ovulation, ending the follicular phase and beginning the luteal phase. Again, this could happen anywhere between day 10 and 23 of your cycle, but on average happens around day 15. 

During the luteal phase, the follicle that just released the egg turns into the corpus luteum, whose new job is to release progesterone. We’ve already heard about the amazing role of progesterone. This phase lasts about 10-16 days, with 13 days being average. The cool thing about this phase is it is the same month to month. So as you get to know your body and your cycle, you can accurately predict the exact day your period will start once you have confirmed ovulation.

If you add it all up, the entire ordeal lasts around 24-35 days, with 29 days being average.

The Fertile Window

As you can see from the little menstrual cycle rundown, ovulation happens on one specific day during the cycle. If the egg is not fertilized within 12-24 hours, it disintegrates and comes out with the period. However, our species may not have survived if we had to time everything down to the very day. This is why we have cervical mucus. Cervical mucus can keep sperm alive for up to five days, meaning each person has at most about 6 days of fertility per cycle (assuming they have mucus the entire 5 days prior to ovulation).

The Pill

She includes two chapters on “The Pill” (a.k.a. Hormonal contraceptives). One about how it affects fertility, and one about how to get off it. This information put me in a fit of rage the first time I read it. Not really, but almost… It is crazy learning about the history of the pill and what it is doing to so many women! It makes me sad that we don’t know and we’re not told. I’m all about informed consent and boy do these chapters deliver. 

Hormonal contraceptives suppress or prevent ovulation, so you already know right there you’ll be missing out on those benefits. But what else might they be causing?

  • Deep-vein thrombosis
  • Stroke
  • Lower libido
  • Decreased testosterone
  • Shrinkage of the clitoris and surrounding vulvar tissues 
  • Anxiety and depression
  • Nutrient deficiencies
  • Higher rates of cervical, breast, and liver cancer
  • Lower rates of ovarian, endometrial, and colorectal cancer (finally, a potential benefit)

I like the way she puts it in this chapter, “Since HC’s affect every woman who takes them, it’s not a question of whether you’ll have side effects – it’s which ones.”

To be clear, you certainly have the right to use the pill and you don’t have to defend that choice to anyone. But without all the information, it’s not a real choice.

Tell Me More

I have barely scratched the surface of the information she shares in this book, which is why you truly need to go read it yourself! Let me just tell you the titles of a few of the chapters I haven’t even mentioned yet: 

  • What is Fertility Awareness? (where she explains the 3 main fertile signs and how to track them)
  • Your Menstrual Cycle as a Diagnostic Tool 
  • Improving Cervical Mucus Production
  • Nutrition for Healthy Cycles
  • Lifestyle Choices for Healthy Cycles
  • Managing Period Pain
  • Managing PMS Naturally
  • Restoring Normal Menstrual Cycles
  • Planning Ahead for Pregnancy

And more! Seriously! Everything you could want to know while still being easy to understand and apply without completely overwhelming you.

The Bottom Line

Clearly, this book is a 5/5 for me. I use the information I learned in it on a daily basis as I observe my cycle! I love knowing what is going on with my health and having tools to address my needs. If you read it, let me know what you think!

The Fifth Vital Sign: Master Your Cycles & Optimize Your Fertility: Hendrickson-Jack, Lisa, Briden ND, Lara: 9781999428006: Books (not affiliate)

About the author

Hey! My name is Brittan and I live in Utah with my husband and one adorable toddler. I love finding holistic and natural ways to care for myself and my family. I particularly enjoy learning about nutrition, herbal medicine, the emotional, spiritual, and energetic aspects of health, and anything else that contributes to complete wellness. Thanks for joining me!

I am not a doctor. Everything I write about is from my personal experience and perspective. Consult a physician if you have questions specific to your health.

One Comment

  • Amanda says:

    Thank you so much for sharing this review. It is sad how very little we know about our menstrual cycle. I’ve been lucky to have an easy menstrual cycle so I haven’t done much research on it, but I as I have clients that have issues, I want to learn more. I look forward to reading this book and helping educate myself and other women.

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