Understanding the Changes In Hormone Levels During Perimenopause

Understanding the Changes In Hormone Levels During Perimenopause

Many physical and chemical changes happen in the body during perimenopause. Perimenopause translates to “around menopause” and is the time frame leading up to menopause. Menopause is marked by 12 consecutive months without a period. 

Estrogen, a hormone that undergoes significant changes as we age, primarily contributes to the symptoms experienced during the perimenopause stage. Other crucial hormones are involved, and analyzing their levels enables doctors to determine your position on the menopause spectrum more accurately.


Perimenopause Hormone Basics 

Hormones are your body’s chemical messengers. They travel in the bloodstream and carry out their effects on an organ or tissue, work slowly over time, and affect many biological processes (1).

During perimenopause, symptoms are brought on by fluctuations in estrogen, a hormone primarily produced in the ovaries. Along with progesterone, estrogen plays a major role in your reproductive health (2).


Estrogen Levels in Perimenopause  

Estrogen is the primary sex hormone for those assigned female at birth. Levels fluctuate during every menstrual cycle, and in perimenopause, estrogen levels will fluctuate irregularly but demonstrate an overall downward trend until they reach a more consistent low level once you hit menopause. 

At different points throughout the perimenopause journey, levels of estrogen peak and fall sporadically. They may even reach concentrations higher than where they were during your reproductive years. Perimenopause can last several years, and once menopause is reached (12 consecutive months without a period), estrogen levels will be so low that you will no longer ovulate (2). 

Due to the overall decline in estrogen, you may start to experience symptoms, including (2):

  • Hot flashes
  • Difficulty sleeping
  • Mood changes
  • Irregular periods
  • Muscle pain
  • Joint aches
  • Vaginal irritation

Progesterone Levels in Perimenopause  

Progesterone is a hormone also produced by your ovaries. The estrogen decline in perimenopause throws off the balance between estrogen and progesterone. These hormones, together, are responsible for ovulation and menstruation. To a lesser degree, progesterone levels also fluctuate during perimenopause and follow an overall downward trend, just like estrogen (2). The decreases in progesterone can cause periods to become irregular, and you may even experience heavier and longer periods during perimenopause (3).

    What Level of FSH Indicates Perimenopause? 

    In addition to estrogen, Follicular Stimulating Hormone (FSH) plays a key role in regulating ovulation. FSH stimulates the ovaries to release an egg during ovulation (4). Hormone levels can seem like they are on a rollercoaster during perimenopause, and sometimes your doctor will test your FSH to confirm where you are in the menopause journey. FSH levels can be elevated during perimenopause, and your doctor may order a test to check your levels. However, a single FSH reading during perimenopause can be misleading. 

    Your estrogen and FSH levels don’t fall at a steady rate from day to day, and levels can vary greatly over perimenopause. In general, when a woman’s FSH blood level is consistently elevated to 30mIU/mL or higher, and she has not had a period for a year, it is generally accepted that she has reached menopause (5).


    Hormone Levels During Perimenopause

    At the beginning of perimenopause, estrogen and progesterone levels remain similar to your reproductive years. Eventually, your body will begin to produce less and less, and over time, not enough will be produced to support ovulation and menstruation. However, you will never be completely without estrogen and progesterone. 

    Although you will be producing significantly less, there will be enough to upkeep vital functions, but once menopause is reached, this will mark the end of the reproductive cycles in females. 


    1. U.S. National Library of Medicine. (2016, October 7). Hormones | endocrine glands. MedlinePlus. https://medlineplus.gov/hormones.html 
    2. Cleveland Clinic. (n.d.). Estrogen: Hormone, function, Levels & Imbalances. Estrogen. https://my.clevelandclinic.org/health/body/22353-estrogen     
    3. The North American Menopause Society NAMS. (n.d.). Changes in hormone levels. Changes in Hormone Levels, Sexual Side Effects of Menopause. https://www.menopause.org/for-women/sexual-health-menopause-online/changes-at-midlife/changes-in-hormone-levels 
    4. U.S. National Library of Medicine. (2020, December 17). Follicle-stimulating hormone (FSH) levels test: Medlineplus medical test. MedlinePlus. https://medlineplus.gov/lab-tests/follicle-stimulating-hormone-fsh-levels-test/        
    5. The North American Menopause Society, NAMS. (n.d.). How Do I Know I’m in Menopause? . https://www.menopause.org/for-women/menopauseflashes/menopause-symptoms-and-treatments/how-do-i-know-when-i'm-in-menopause-