Why Does Progesterone Decrease In Perimenopause?

You may already know that your hormones start to shift as you move into and through your 40s. Progesterone is one of first hormones to start changing as you move past late 30s, it starts to decline. You might ask why does progesterone decrease in perimenopause? And this is a really important part of perimenopause physiology to understand and manage. In a previous blog, I explained what’s happening with both oestrogen and progesterone in perimenopause. In this blog however, I’m going to focus solely on progesterone. I’ll explain what progesterone is, what is does, why it declines, and how to help counteract this for a smoother and happier perimenopause! Trust me, it’s possible, you just need to know what to do 😉


Progesterone is a steroid hormone. ‘Steroid hormone’ refers to a group of hormones derived (made) from cholesterol that act as chemical messengers in the body. 

Progesterone converts into a brain hormone called allopregnanolone, which increases the actions of GABA, a calming, anti-anxiety and sleep-supportive brain chemical. Without allopregnanolone, the body’s stress response system can become destabilised. This can soon result in a reduced ability to cope with stress and issues getting to sleep at night and or staying asleep. Progesterone is also anti-inflammatory, supports cognition, thyroid and metabolism and prevents water retention (‘puffiness’).

Progesterone is the yin to oestrogen’s yang, sheltering the body and breast tissues from the effects of too much oestrogen. If oestrogen is met with progesterone (ovulation occurs), these symptoms are minimised.

Some studies show that low progesterone may lead to irregular and or much heavier periods than normal during perimenopause.


The main function of progesterone is to prepare the lining of your uterus (endometrium) to allow a fertilised egg to implant and grow. Progesterone makes this lining fluffy and hospitable for the egg to settle in, get cosy and grow. If pregnancy does not occur after ovulation, the endometrium sheds, marking day 1 of your bleed and the start of a new cycle. If pregnancy does occur, progesterone levels increase in order to support the pregnancy.

HOWEVER!! Progesterone is needed for so much more than just pregnancy. Your body and brain need this wonderful for hormone to:

  • Prevent oestrogen from being left unopposed (not balanced out by its partner hormone), also known as ‘oestrogen dominance’
  • Promote a sense of contentment, equilibrium and well-being
  • Support deep, restful REM sleep
  • Increase a brain chemical called GABA, which reduces anxiety and promotes calm and relaxation
  • Support cognition (your brain!) and concentration
  • Boost metabolism through its thermogenic (raising of body temperature) actions
  • Help your thyroid gland to make enough thyroid hormone
  • Help you release excess body fluid (preventing ‘puffiness’)
  • Protect nerve cells and support healthy blood flow to the brain

When progesterone is low or you didn’t make any one or multiple months, you may experience:

  • Trouble sleeping / insomnia particularly during the second half of your cycle
  • Anxiety, particularly heightened during the second half of your cycle
  • Symptoms of unopposed oestrogen/oestrogen dominance (miserable, heavy periods, clotting, breast pain, mood swings, headaches, rage, fibroid growth, cyst growth)
  • Feeling more stress-sensitive
  • Irritability
  • Migraines just before or during your period
  • Water retention / ‘puffy’ ankles and hands etc.
  • Spotting or breakthrough bleeding during the second half of your cycle
  • Shorter cycles (less than 25 days)
  • Long or irregular cycles due to less frequent ovulation


Oestrogen is made everyday as part of your menstrual cycle, with levels ramping up as your body gears up to ovulate just before the midway point of your cycle. Whether or not one of your ovaries releases an egg (ovulation), that oestrogen will still have been made. Progesterone however, is ONLY made IF you do actually ovulate. So, ovulation is HOW your body makes progesterone. Therefore, supporting your body to ovulate each month is how you support healthy progesterone levels.

During ovulation, a unique little temporary gland is formed, called the corpus luteum. This amazing little gland allows one of your ovaries to release a nice load of progesterone into your system after ovulation. The corpus luteum forms very quickly and lives for about 11-14 days (the approximate length of the luteal phase of your cycle), where it continues to release progesterone into your system.

Sometimes, you manage to ovulate but the corpus luteum formation is less than optimal, resulting in less that optimal levels of progesterone being made. The formation of the corpus luteum demands a lot of energy (food/calories) from three well rounded, nutrient-rich meals. Daily meals containing optimal protein, healthy fats, quality carbohydrates, and nutrients such as cholesterol, B-vitamins, coQ10, vitamin D, iodine, magnesium, selenium and zinc are essential for a healthy corpus luteum.

No ovulation means no progesterone production.

The diagram below shows an average 28 day menstrual cycle (normal cycles range from 24 – 35 days so don’t worry if yours isn’t 28 days!). Here you can see that after ovulation, oestrogen is met with lots of progesterone, which is reflected in the grey line. Had this person not managed to ovulate, the grey line would have remained flat throughout the entire cycle, creating an oestrogen ‘dominant’ situation, likely resulting in PMS, breast pain, mood swings, headaches and heavy flow, potentially with some clotting. PLUS symptoms of low/no progesterone, which include trouble sleeping, anxiety, irritability and low mood, water retention, and brain fog.

NOTE: If you are on the oral contraceptive pill or injection, brain to ovary communication is shut down in order to suppress ovulation, which means you won’t have the natural cycling of hormones shown in the diagram. There’s also no progesterone if you’re on almost any type of hormonal contraception, including the implant and hormonal IUD, because the progestins contained in these meds are NOT the same as progesterone.

It’s possible to track whether or not you’ve ovulated by way of taking your temperature each morning as soon as you wake up (before getting out of bed) and noting it down, known as ‘basal body temperature tracking’. Once you have a good idea of your baseline morning temperature from day 1 of your cycle through to just before ovulation (the follicular phase), you’ll be able to see if there has been a slight increase in temperature (between about 0.1°C to 0.3°C higher) after your estimated ovulation day. This would suggest that you did ovulate and therefore make progesterone, this is because progesterone increases body temperature.


As you approach your late 30s and move into your 40s, one of the first hormonal shifts that starts to occur is a decline in progesterone. Hopefully by now you can appreciate the significance of this on physical, mental, and emotional wellbeing.

So, why does progesterone decrease in perimenopause? Simply put, because ovulation starts to become harder and harder to achieve as you move past 40. This is due to the change in communication between your brain and your ovaries that starts to occur from mid to late 30s onwards. The brain no longer talks to the ovaries as loudly, clearly and timely as it did in your 20s and earlier 30s, and your ovaries no longer respond as well as they did before.

But the good news is that you can support your body to ovulate more months than it might have done had you not intervened. This is the beauty of nutrition and lifestyle habits – you can leverage them to support your body to ovulate despite the fact that is does become harder to achieve after 40. Isn’t that just great?


Remember, the key thing to understand when it comes to progesterone production, is that ovulation is literally how you make it. Therefore, supporting your body to ovulate each month is how you support healthy progesterone levels.

Here are 5 ways to support ovulation:

1) Manage Stress And Minimise Its Impact

This is a BIG one because chronic stress is one of the BIGGEST blockers to ovulation. Why? Because your brain is always scanning your environment for any threats to yours or a potential baby’s survival. The annoying thing is that we can’t just tell our brain that we are not actually trying to become pregnant, we just want to ovulate so we can have progesterone! The brain also cannot be told that certain day to day stressors are not actually life threatening, such as having too much on your plate, working long hours, financial worries, work or relationship issues, ageing parents, troublesome teenagers, traffic jams, running late, etc.

All of these stressors are considered a threat by the brain, which results in the brain NOT sending the signals to your ovaries to go ahead and ovulate. no ovulation occurs, no progesterone is made, and oestrogen is left unopposed and dominates the second half of your cycle, and BAM…symptoms discussed above ensue and your next period is a heavy one.

Here are some of my favourite ways to manage and reduce your physiological stress response each day:

  • Regular deep breathing exercises such as the 4:6 or 4-7-8 techniques done for 3 minutes morning and night
  • Mindful walks in nature or any kind of green space or woodland, even just 10 minutes
  • Gentle yoga, Tai Chi, or Qigong, even just 10 minutes
  • Saying or writing some things you are grateful in your day and or your life as a whole, morning and night
  • Yoga Nidra (also called non-sleep deep rest) lying down meditations
  • 5 – 10 minutes lying on the floor with your legs resting up the wall whilst focusing on your breath
  • Candlelight baths in epsom salts

2) Support Thyroid Health

Look out for a future blog specifically on this and this is a whole other topic in itself but for now, know that you should be keeping an eye on important thyroid function markers such as T4, T3, TSH and the 2 main thyroid antibodies; anti-thyroid peroxidase (TPOAb), anti-thyroglobulin antibody (TgAb). Conventional thyroid testing only looks at TSH and T4, which doesn’t provide the full picture so you would need to go private for a more comprehensive panel. I use Genova Diagnostics with my clients and for a DIY version I recommend Medichecks. Thyroid issues can block ovulation and or drive symptoms of oestrogen dominance including PMS and heavy and painful periods.

3) Prevent Or Reverse Insulin Resistance

For a deeper dive into insulin resistance and why it matters, you can click here. Essentially, managing insulin resistance comes down to eating a blood sugar balancing diet with optimal protein, healthy fats, colourful vegetables and ‘complex’ or slow-release carbohydrates, in a healthy serving size. Avoiding snacking, fasting for 12-16 hours overnight and lifting weights are also super helpful. Insulin resistance can block ovulation and or drive PMS symptoms and heavy, painful periods.

4) Eat A Nourishing Balanced Diet With ENOUGH Food (calories)

I often get asked what’s the best way to eat during perimenopause. This can be a difficult question to answer definitively because we are all so unique and there are likely nuances needed for most. However, there are certainly some general nutrition guidelines that all women would benefit from adhering to. Preventing or minimising progesterone’s decrease in perimenopause is a key way to have. much better experience overall. What’s important to appreciate is that perimenopause is NOT a time for low calorie diets and restriction. Now more than ever we should be eating a nourishing diet made up of quality proteins (every meal, minimum 30g protein per meal, preferably including all animal proteins), nutrient-dense, slow-release carbohydrates, healthy fats and colourful vegetables. For a deeper dive into the best diet for perimenopause, read my blog here.

5) Identify And Address Potential Underlying Issues / Dig Deeper

Another reason for progesterone decrease in perimenopause can be unaddressed chronic inflammation, which can block ovulation and or prevent optimal corpus luteum formation, therefore it’s important to identify and address potential sources of persistent, low-grade inflammation such as:

  • An autoimmune condition, including Hashimoto’s (thyroid autoimmunity)
  • Unknown sensitivity to cow’s milk or gluten
  • Gut intestinal permeability (also known as ‘leaky gut’)
  • Insulin resistance and or type 2 diabetes
  • Gut infections (pathogenic bacteria, parasites, yeast, dysbiosis, H.Pylori)
  • Viral infections

I hope this blog has given you good insight into why progesterone decreases in perimenopause, why you need it, and how to optimise it. If you would like my help and support, the Perimenopause Roadmap is a great place to start. Click here to learn more about it and sign up. If you have any questions, feel free to email me at To find out more about my 3 or 6 month coaching packages, click here.

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.

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