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  • Writer's pictureDr. Susan Caldwell

How Charting Your Cycles Could Help Prevent Breast Cancer

During the month of October, we see an abundance of pink ribbons intended to make us more aware of the reality of breast cancer. Women are reminded to have their annual mammogram to detect cancer early so that it can be treated or even cured in the early stages. Breast cancer is very common. In fact, in America, it is the leading cause of cancer in women. One out of every eight women will be diagnosed with breast cancer. Our modern health care system focuses on the detection and treatment of breast cancer, but rarely do you hear about what women can do to prevent breast cancer. This is unfortunate because now we have much more understanding of the environmental factors that can increase a woman’s risk of being diagnosed with breast cancer. When women understand their own individual risks, they can work to lower their risk of breast cancer long before their first mammogram at age 40.

The Link Between Low Progesterone, Infertility and Breast Cancer

In 1981, a Johns Hopkins study followed more than 1000 women with infertility to determine the incidence of breast cancer in that group. They divided the women into two groups: low progesterone (PD) versus non-hormonal (NH) causes of infertility. “Women in the PD group had 5.4 times the risk of premenopausal breast cancer compared to women in the NH group. This excess risk could not be explained by differences between the two groups in ages at menarche or menopause, history of oral contraceptive use, history of benign breast disease or age at first birth. Women in the PD group also experienced a 10-fold increase in deaths from all malignant neoplasms compared to the NH group.”

The implications of this study are HUGE for all women! It underscores the importance of testing and treating women with low progesterone throughout their reproductive years. The results of this study suggest that progesterone is protective against cancer. But how does this work? One way is by opposing the effects of estrogen. In many organs including breast and uterus, estrogen causes growth and proliferation of new cells and progesterone opposes these effects and stimulates maturation and stability of the growth of the tissues in the same organs. For example, women with polycystic ovarian syndrome and long cycles are at risk for uterine cancer because they often produce much more estrogen relative to progesterone. The uterine lining is exposed to weeks or months of estrogen made by the ovaries without the balancing effect of progesterone (because ovulation does not occur every month). This causes the lining of the uterus to grow unchecked by the effects of progesterone which causes the lining to mature and then to shed every month.

Who should be tested for low progesterone?

Women with signs and symptoms of low progesterone should be tested. Before I became a Naprotechnology medical consultant, I had no idea how to identify the signs and symptoms of low progesterone. Most women either ignore these symptoms or they tell them to their doctor who has not been trained to recognize, test or to treat the symptoms. I am quite confident that this will change in the coming years, but not until more women are taught to recognize the symptoms of low progesterone.

What are the signs and symptoms of low progesterone?

Here are the most common symptoms that accompany low progesterone in women:

Premenstrual Syndrome


Heavy Periods

Unusual spotting (especially right before or right after the period)

Postpartum Depression/Anxiety

Irregular cycles - short or long cycles

Recurrent Miscarriage



Excess cervical mucus after ovulation

Unfortunately, most women suffering from these symptoms do not have their progesterone levels checked (because very few doctors are taught how to do this). Instead, they are given birth control, medications for anxiety or are referred to a fertility specialist who recommends in vitro fertilization for infertility. None of these interventions can identify and treat the underlying problemlow progesterone.

How can a woman know her progesterone level?

Progesterone is a hormone that is made by the ovary at a very specific time in the cycle - after ovulation. It begins to be made after ovulation by the corpus luteum (the cyst that remains after the egg is released from the ovary) and can be measured in the blood over the next 2 weeks or so. To get an accurate measurement of this hormone, a woman must be charting her cycles using a method that is taught by a certified teacher who is an expert in one of the methods of fertility appreciation/awareness such as the Creighton Model Fertility Care System. It is very difficult to accurately identify ovulation using a DIY method such as a calendar-based app on a mobile device.

Once ovulation is accurately identified using her chosen method, a woman should see a physician or health care professional who is certified in a method such as Naprotechnology. In my practice, this is the typical process:

  • Learn charting with a teacher for approximately 2 months

  • Visit with me to review charts and to order labs

  • Patient visits the lab (starting 3 days after her ovulation day) every other day until the 11th day after ovulation

  • Patient returns to review results and discuss treatment

  • Patient returns after 2 months of treatment to review chart and repeat lab to be sure that her progesterone is in the normal range with treatment

What is the treatment for low progesterone?

It is VERY IMPORTANT that women are treated with actual progesterone and NOT progestins such as medroxyprogesterone, Depo-Provera injections or birth control pills. Most doctors are not aware that these medications have very different effects in a woman’s body than does actual progesterone. Progestins have been shown to significantly increase the risk of breast cancer in large studies in the United States and Europe. Progesterone is a unique hormone made by the ovaries whereas progestins are synthetic ‘‘knock-offs’’ of progesterone made in a laboratory and have very different effects in a woman’s body.

In my practice, I treat patients who are diagnosed with low progesterone with progesterone (given orally, vaginally or intramuscularly) according to the various protocols of Naprotechnology. If a patient has low estrogen levels, we generally treat with injections of the hormone HCG. This is a very effective treatment for certain patients.

What about genetics and breast cancer?

Most women who are diagnosed with breast cancer DO NOT have breast cancer in their family. More than 90% of breast cancers are NOT due to genetic factors but are due to our lifestyle choices and our environment. Even in women who are genetically predisposed to be diagnosed with breast cancer, there is much they can do to prevent the expression of the genes that would otherwise lead to cancer. The field of epigenetics is fascinating and teaches us that our genes are inherited at conception from our parents, but we can alter the expression of those genes by our lifestyle choices – how we take care of ourselves with diet, exercise, etc. Just because your relatives had breast cancer does not mean that you should wait in fear hoping that you avoid the same fate. There is so much power in knowing the risks and how to avoid them with a proactive, hopeful outlook.

What are other ways to prevent breast cancer?

Here are some tidbits of information that you might find useful:

Avoid using hormonal birth control!!! Read about how taking birth control, especially before your first pregnancy, can significantly increase the risk of breast cancer.


Whole foods, plant-based, anti-inflammatory, avoid trans fats (processed foods)

Organic when possible

Avoid storing and cooking food in plastics

High fiber

Food high in vit E; Omega 3 and 6’s

Drinking coffee may help prevent breast cancer in some studies

Alcohol – women who have 3 drinks/week have a 15% higher incidence of breast cancer (

Avoid high fructose corn syrup

Limit red meat intake


Up to 25% risk reduction with exercise according to this study.


Working nights increases the risk of many different cancers.

Vitamin D

Taking vitamin D can cause up to a 50% risk reduction in breast cancer. Be sure to measure the 25-OH vit D level, the optimal range is 50-100. There is an inverse relationship between low vitamin D and risk of breast cancer


Taking low-dose aspirin (81mg) every other day may reduce the risk of breast cancer in this study.

I hope you feel more empowered to take your own steps to prevent breast cancer after reading this information. There is so much power in knowing how your hormones affect your overall health. It is a great time to start charting and learning about your hormones. Check out this great new resource to get started learning more about fertility awareness methods and choose the best one for you!! Do you like podcasts? I love this one!!

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