What Progesterone Does And Why It Declines In Your 40s

In this blog I’m going to explain what happens during peri menopause, specifically with regards to the hormone progesterone.

In a previous blog called ‘what is perimenopause’, I explain what’s actually happening with your hormones (oestrogen and progesterone) once you pass age 35 and move through your 40s. In the blog, I explain why you need progesterone, how you make it, why it starts to decline in your 40s, and how to support its production.


Oestrogen and progesterone work TOGETHER in your body to exert health protective effects, so we really mustn’t forget about or overlook amazing progesterone.

It’s easier for the body (ovaries) to make oestrogen than it is to make progesterone, because oestrogen is made in the build up to ovulation whether you actually go on to ovulate or not, whereas progesterone is ONLY made IF you ovulate and ovulation becomes harder to achieve in your 40s.

During ovulation, a unique, small temporary gland, called the corpus luteum, is formed, which allows one of your ovaries to release a load of progesterone into your system after ovulation. The corpus luteum forms very quickly and lives for about 11-14 days (the luteal phase of the cycle) where it continues to make progesterone. If you are tracking your basal body temperature as mentioned above, these are the days you will see that spike in temperature. The formation of the corpus luteum demands a lot of energy (good food!) and nutrients such as cholesterol, B-vitamins, coQ10, vitamin D, iodine, magnesium, selenium and zinc, so these are key nutrients to make sure you’re getting from your diet each day.

What happens if you don’t ovulate?

If/when you don’t ovulate, you don’t make progesterone, which leaves oestrogen ‘unopposed’ or not balanced out by its partner hormone. This situation is sometimes referred to as ‘oestrogen dominance’, which doesn’t necessarily mean you have high levels of oestrogen, but simply that oestrogen is not balanced with progesterone. Unopposed oestrogen results in symptoms such as breast pain, heavy and or painful periods, mood swings and headaches.

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 was 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 and likely PMS, breast pain, mood swings, headaches and heavy flow once the period arrived. 

Add to this, 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, your 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.

You see, 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.

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, resulting in 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’).

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

Achieving ovulation becomes harder and harder to achieve the further you progress through your 40s and the closer to menopause. This means many more months with unopposed oestrogen where not only is oestrogen on a roller coaster, it’s also dominating the hormone show and exacerbating all of the symptoms already discussed.

The good news is that you can support your body to ovulate more months than it might have done otherwise. AND even if you don’t manage to improve your ovulation status, the same set of nutrition and lifestyle habits that support ovulation also support a reduction in symptoms of oestrogen dominance and low progesterone – YAY!


Your menstrual cycle and periods can appear completely normal even though you haven’t ovulated (some or many months). So, you won’t know if you’ve managed to ovulate month to month unless you’re tracking your cycles and taking your basal body temperature each morning. With basal (first thing before moving from the bed) body temperature, you’re looking for a lower reading from a few days before your period and up to the time you’re due to ovulate. Following successful ovulation, you should see a spike in basal temperature more or less straight away or a day or so later. The rise in temperature usually lasts around 11 or so days. If your temperature did not change, you can assume ovulation didn’t occur.


I need to say this again because it’s so important; some simple but important nutrition and lifestyle habits can support your body to ovulate more months than it might have done otherwise. AND even if you don’t manage to improve your ovulation status, the same set of habits also support a reduction in symptoms of oestrogen dominance and low progesterone.

Here are some of the best ways to support ovulation (and horrible perimenopause symptoms generally!):

1) Manage your stressors and minimise its impact.
This is a BIG one because chronic stress is probably THE BIGGEST blocker 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 your brain doesn’t know the difference between being chased by a sabre-toothed tiger and being stuck in traffic, being late for work, missing a deadline, juggling work and family life, worrying about the state of your finances or negative relationships. All of these are seen as a threat by your brain, resulting in your brain NOT telling your ovaries to go ahead and ovulate. Now you have all this oestrogen and no progesterone to meet it for the second half of your cycle and BAM…symptoms ensue and your next period is a heavy one.

Best ways to manage stress:

Regular deep breathing exercises such as the 4:6 or 4-7-8 techniques.
Done daily; first thing in the morning, in the middle of the day and last thing at night, these simple, short techniques can be powerful ways to bring down your stress hormones and rebalance cortisol. Deep, slow breathing tells your brain there is no threat, making it more likely that it WILL instruct your ovaries to ovulate.

Go walking in nature/green spaces.
Try to do this everyday if you can. Studies show that being in nature, e.g. green spaces (local park or common), forests and woodlands, reduces stress hormones such as adrenaline and cortisol and switches you out of the ‘fight or flight’ nervous system activation into “rest and repair” mode instead. Again, making it more likely your brain WILL instruct your ovaries to ovulate.

Nourishing practices such as yoga, qigong, tai chi, and other mindful and meditative activities, done regularly, will have the same positive impact on your nervous system, making it more likely your brain WILL instruct your ovaries to ovulate. Other great practices to incorporate into your days include writing down or saying a few things you’re grateful for at the start and end of every day, soaking in an epsom salts bath in candlelight and gentle music or meditation, and ‘Yoga Nidra’ body scan meditations.

I hope that you can see the importance of mitigating the impact of stress and how powerful and important these practices actually ARE for you, now more than ever.

2) Support your thyroid health.
Look out for a 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 thyroid antibodies. Conventional testing only looks at TSH and T4, which really 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. An underactive thyroid can block ovulation and or drive symptoms of oestrogen dominance including PMS and heavy and painful periods.

3) Prevent or reverse insulin resistance.
This is another topic that needs its own blog (coming soon). Essentially this comes down to eating a blood sugar balancing diet with optimal protein, healthy fats, colourful vegetables and using ‘complex’/slow-release carbohydrates only and in healthy amounts. Avoiding snacking, fasting for 12-16 hours overnight and lifting weights are also helpful. Insulin resistance can block ovulation and or drive symptoms of oestrogen dominance including PMS and heavy and painful periods.

4) Be well nourished with ENOUGH food (calories) and nutrients.
I often get asked what’s the best nutrition during perimenopause and what’s important to appreciate here is that perimenopause is NOT the time for low calorie diets and restriction. Eat 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.

5) Identify and address potential underlying issues.
Such as chronic inflammation and stress-states from a dairy or gluten sensitivity, insulin resistance, less than optimal gut health and a ‘leaky’ gut lining, and underactive thyroid.

If you would like my help, the Perimenopause Roadmap is a great place to start and may even be all you need. Click here to check it out.

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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