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Let’s talk about Estrogen

1 July 2022 | 18 mins read | Let’s talk about Estrogen

Estrogen is a hormone that affects our bodies differently in each of the various phases of our lives. It plays one role while we are still in the womb, has an impact on puberty, on our reproductive years, on pregnancy and childbirth, on perimenopause, menopause, and on our post-menopausal years. 



Estrogen is the main female sex hormone.  A hormone is a “chemical messenger” that travels through the bloodstream to deliver instructions to the cells in target tissues or organs.  Estrogen is called a sex hormone because it is produced mainly in the ovaries and affects the development of our reproductive systems.  It also affects the development of secondary female sex characteristics such as breasts and wider hips.  

Males also produce estrogen, but in much smaller quantities.  Likewise, females produce testosterone, the main male sex hormone, in much smaller quantities than in men.  

Although estrogen is a sex hormone, it affects numerous seemingly unrelated functions throughout the lifespan. This is because cells in tissues and organs that respond to estrogen such as the genital tract, the brain, the urinary tract, and the blood vessels all have estrogen ‘receptors’.  Estrogen binds to the receptors, causing a specific action to take place within the cell.  Most of these actions are necessary and desirable, but estrogen can also have undesirable effects, particularly at high levels.



There are three different types of estrogen, and each plays a different role in the body. 

1) Estradiol: Estradiol is the strongest form of estrogen, and the dominant one during the reproductive years.  It is primarily produced in the ovaries by the dominant ovarian follicle – the follicle which will produce that menstrual cycle’s egg. Estradiol levels decrease significantly during menopause.  

Estradiol’s beneficial functions, often in combination with other hormones, include:  

  • Guiding the development of the reproductive system. 
  • Signaling for the release of mature eggs from the ovaries during the ovulation phase of the menstrual cycle. 
  • Promoting thickening of the uterine lining so that a fertilized egg can implant.
  • Increasing HDL (‘good’) cholesterol and reducing LDL (‘bad’) cholesterol. 
  • Dilating blood vessels to promote good circulation. 
  • Preventing calcium loss, which in turn keeps bones strong.

2) Estriol:  Estriol is the weakest type of estrogen but its role in pregnancy is critical.  During pregnancy the fetus produces a chemical that travels to the uterine placenta.  In the placenta, the fetus-produced chemical is converted into estriol.  From the placenta, estriol moves into the bloodstream.   

  • Estriol allows the uterus to expand as the fetus grows and enlarges the milk ducts in the breast in preparation for milk production. 
  • Estriol makes the body more sensitive to other important pregnancy hormones. 
  • During the second trimester estriol can be measured as part of a screening test for certain birth defects. 


3) Estrone: Estrone is the only form of estrogen that the body continues to make after menopause.  Estrone is a weak estrogen that can convert into estradiol if the body needs a more powerful form of estrogen. 



Having too much estrogen is most likely to occur before menopause. Symptoms of too much estrogen include: 

  • Heavy or light bleeding during the menstrual period. 
  • Acne. 
  • Constipation. 
  • Low libido (sex drive). 
  • Cystic breasts. 
  • Benign uterine tumors called fibroids. 
  • Anxiety and/or depression. 
  • Fatigue. 
  • Weight gain especially in the thighs, hips, or waist.

Very high levels of estradiol increase the risk of cardiovascular disease. 

Adipose (fatty) tissue produces estrone. Both too much estrone and too much estradiol have been implicated in breast cancer and endometrial cancer (cancer of the uterine lining).  



In younger women, symptoms are similar to those of menopausal or post-menopausal women.  The main difference is that younger women may have irregular or missed periods rather than no periods.  Causes of low estrogen in younger women include:  

  • Surgical removal of the ovaries. 
  • Chemotherapy. 
  • Radiation. 
  • Certain medications. 
  • Premature ovarian failure. 
  • Endocrine abnormalities.

In pre-pubertal girls, low estrogen levels can cause slow bone growth and delayed puberty. 



Estrogen levels fluctuate during perimenopause, and gradually decrease through menopause. In postmenopausal women, estradiol levels are approximately 95% lower than in premenopausal women.  This is a normal consequence of aging, but brings with it some less-than-desirable symptoms.  

  • Blood supply to the genital area decreases, leading to a decrease in libido. 
  • Vaginal moisture decreases. Vaginal dryness can cause discomfort during intercourse and can increase the risk of infection. 
  • Hot flashes or night sweats occur. A decrease in estrogen below previously higher levels disrupts temperature regulation.  When the body’s core temperature rises by even a small amount, the body tries to protect the core by dissipating heat away to the periphery, towards the skin.  Warmth at the periphery induces sweating, helping to cool the core.    
  • Mood swings begin or increase.  Some mood swings can be a result of sleep that is disrupted by night sweats.  Loss of sleep is a well- known contributor to mood dysregulation. 
  • Urinary urgency, discomfort while urinating, and urinary tract infections become more common.  
  • Skin becomes less elastic, and wrinkles become more noticeable.



Yes. In fact, hormone replacement therapy (HRT) used to be widely recommended to women as they entered menopause, in order to protect against heart disease.  However, studies have shown that for most women the risk of developing breast cancer and blood clots from HRT exceeds the long-term cardiovascular benefits.  Studies are ongoing, and women should speak with their health care providers about their individual risks. 

Estrogen is effective in improving menopausal symptoms that can be intolerable or dangerously unhealthy for some women.  Benefits of estrogen therapy include: 

  • Minimizing hot flashes and night sweats in menopause.
  • Preventing osteoporosis in post-menopausal women. (LINK?)
  • Preventing urinary urgency or UTIs (LINK).
  • Treating vaginal dryness and vulvovaginal atrophy.  Topical prescriptions are available which have minimal impact on blood levels of estrogen and are less likely to cause adverse effects.


  • Transitioning from male to female.  Estrogen helps with the development of female secondary sex characteristics. At higher doses estrogen suppresses the naturally occurring testosterone produced by the male gonads. If the male gonads are surgically removed, the estrogen dose can be reduced to levels seen in people assigned female at birth.
  • Birth control.  Estrogen is used in oral contraception, contraceptive patches, and contraceptive vaginal rings, along with another hormone called progestin. In addition to preventing contraception, birth control can also increase the time between periods by several months, can help with period-related migraines, can help to minimize the symptoms of PMS, can limit build-up of endometrial tissue in women who have endometriosis, and can minimize symptoms of polycystic ovarian syndrome such as acne, facial hair, and irregular periods (PCOS).  (LINK to article?)
  • In Vitro Fertilization (IVF).  Oral or vaginal estrogen may be prescribed a few days prior to implantation of the embryo in order to help prepare the uterus for pregnancy.  (LINK to article?)

Estrogen is not without risks.  Estrogen can increase the risk of developing dangerous blood clots that can go to the brain or the lung.  In some women it can increase the risk of breast or cervical cancer.  A male who transitions to female has an increased risk of breast cancer, but her risk is still lower than a lifelong female’s risk.



No matter what your age, it is important to discuss the risks and benefits of estrogen with your health care provider.  The frequency and severity of your symptoms, their impact on your quality of life, the availability of alternative therapies, your health history, and your family’s health history will all be considered in determining whether taking estrogen for any reason is the right decision for you. 



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Jill Garner
Jill GarnerRegistered Nurse and Diabetes Educator