Understanding Heavy Periods In Perimenopause

Have Your Periods Gotten Heavier in Your 40s?

Have your periods become so unpredictable that you’re never sure if you’ll experience spotting, flooding, or some combination of both?

Welcome to perimenopause. With oestrogen levels on a rollercoaster and progesterone on the decline, it’s no wonder periods can become heavier and more erratic during this time.

Understanding the Hormonal Changes

In your 40s, oestrogen can sometimes rise to levels two or three times higher than ever before at certain points in your cycle (see diagram below). Combine this with declining progesterone, and you get oestrogen-dominant cycles, leading to heavier periods. There are other contributing factors for heavy periods in perimenopause, which we’ll explore later in this blog.

Diagram showing how oestrogen can spike to high levels in perimenopause (see red dotted line and circled area).

Diagram showing how oestrogen can spike to high levels in perimenopause (see red dotted line and circled area).

Many people associate perimenopause with low oestrogen, but it actually starts with high and fluctuating oestrogen levels and ends with low levels at menopause.

Oestrogen Spikes and Dominance

In a regular menstrual cycle, oestrogen rises and falls in a relatively consistent manner, met by progesterone in the second half of the cycle. However, in your 40s, the communication between the brain and ovaries changes, causing oestrogen to fluctuate more erratically. This results in cycles that are often dominated by oestrogen, especially when ovulation (and thus progesterone production) does not occur as regularly.

The Role of Low Progesterone in Heavy Periods

If you’ve read my previous blogs, you know that ovulation is the only way the body produces progesterone each month, and progesterone helps protect against heavy periods in perimenopause.

In the first half of the menstrual cycle, the brain releases follicle-stimulating hormone (FSH), encouraging the ovaries to release follicles (containing an egg) and increasing oestrogen levels to thicken the uterine lining. Once ovulation occurs, the ovaries produce progesterone, which prevents further thickening of the uterine lining by oestrogen.

But if ovulation doesn’t occur, no progesterone is made to balance the stimulating effects of oestrogen, leading to “unopposed” oestrogen or oestrogen “dominance”. This situation is more common in perimenopause and becomes increasingly frequent as you approach menopause.

Clotting and Heavy Periods

Without progesterone, the result is an unusually thick uterine lining, leading to heavier, longer, and more intense periods. This excessive buildup of tissue also means that your body can’t keep up with anticoagulant activity, resulting in clotting.

Supporting Progesterone Production

Even though ovulation becomes harder to achieve during perimenopause, it’s not impossible. There are daily practices you can adopt to support ovulation.

Stress is a major factor preventing ovulation. The brain senses any kind of stress, including modern-day chronic stressors such as financial worries, emotional burdens, and dysfunctional relationships, and doesn’t signal the ovaries to release an egg. Managing stress is vital in your 40s.

Additional Causes of Heavy Periods in Perimenopause

1. High Intake of Hormone-Disrupting Chemicals

Hormone-disrupting chemicals mimic oestrogen in the body, causing hormone imbalances and increasing your body’s total oestrogen load. These chemicals can contribute to PMS, heavy periods, and the growth of fibroids and cysts. They are found in products like plastics, personal care products, household cleaning products and detergents, air fresheners, and perfumes.

What can you do?

  • Filter your water (e.g., Brita jug filter or Berkey)
  • Use glass, ceramic, or stainless steel for cooking, heating, storing, and drinking
  • Switch to cleaner skincare brands like Green People, Antipodes, Sukin, Jason, Ren, Neal’s Yard, Tropic, and others
  • Choose cleaner household cleaning and detergent brands such as Bio-D, Method, and Attitude.

2. Iron Deficiency

What’s important to know is that heavy periods can cause iron deficiency and iron deficiency can also make your periods heavier.

What can you do?

  • Get a full iron panel checked with a serum (blood) test that includes iron, total iron-binding capacity (TIBC), and ferritin
  • Increase iron-rich foods (heme iron) or take an iron supplement. Chelated iron is gentle and doesn’t cause gut issues like other forms of iron supplements

3. Inefficient Breakdown and Clearance of Oestrogen

Properly metabolising (breaking down and detoxifying) oestrogen is essential to prevent it from building up in your blood. This process primarily occurs in the liver, as well as the gallbladder and the gut. You can read more about oestrogen detoxification here.

What can you do?

  • Reduce and limit alcohol, as the liver prioritises alcohol detoxification over oestrogen breakdown
  • Support a healthy gut and ensure daily bowel movements

4. Chronic Inflammation

Inflammation can be caused by many things, including inflammatory foods, poor sleep, alcohol, stress, blood sugar imbalance/high insulin, gut bacterial imbalances, chronic bacterial or parasitic gut infections, and autoimmunity.

What can you do?

  • Remove inflammatory foods like processed seed oils, refined carbohydrates, sugar, alcohol, and cow’s dairy. Goat and sheep milk products are usually fine
  • Manage stress
  • Support better sleep
  • Optimise gut health

5. Insulin Resistance / Blood Sugar Dysregulation

Blood sugar imbalances can lead to insulin resistance and chronic inflammation, which is a big block to ovulation.

6. Under- or Over-Active Thyroid

Get a comprehensive thyroid check, including T4, T3, Reverse T3, and thyroid antibodies.

7. Endometriosis or Adenomyosis

You can read more about this here.

Final Thoughts

I hope this blog post has been informative and helpful. If you’ve identified any of the areas that apply to you, you now have a starting point to address heavy periods in your 40s.

Hi, I'm Francesca

I’m a Registered Nutritional Therapist who helps womens in their 40s find vibrant health and vitality, and thrive through perimenopause and beyond.

With nearly 10 years of experience working with hundreds of people, I empower and support women to support their bodies and hormones for a smooth and happy ride in their 4os.

Through our work together, clients have improved their energy, their periods and cycles, their mood, sleep, brain fog and digestion, and learned how to better manage their weight.

I am here to help you get back to YOU so you can have a fantastic time in your 40s.

My signature nutrition and lifestyle coaching approach to supporting women with their health and wellbeing is refreshing, down-to-earth and realistic.

Download the Free Guide

A FREE, no-nonsense PDF guide to Mastering Perimenopause and learn how to master your hormones in your 40s for more energy, better sleep, balanced mood, easier periods and so much more.


Learn more about my signature course – Thrive Through Perimenopause – to start taking care of your hormone health once and for all, for a MUCH smoother ride in your 40s and beyond!

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