KC oestrogen

Oestrogen 101: Everything you need to know about Oestrogen

August 31, 2022Hertility

Key takeaways

  • There are lots of different types of oestrogen, but the main one in women and those assigned-female-at-birth is oestradiol (E2)
  • E2 plays a big role in regulating our menstrual cycles, fertility, libido, skin health, heart health and bone density
  • Our oestrogen levels fluctuate throughout our menstrual cycles and also naturally decline with age 
  • Imbalances in oestrogen levels are common and can be due to various underlying health conditions, medications and dietary or lifestyle factors
  • Testing your oestrogen levels can help you figure out if you have an imbalance and see if you E2 levels could be impacting your fertility

Skin got that golden hour glow? Feeling frisky? Looking fabulous? Chances are, you’ve got oestrogen to thank.

Oestrogen truly is the matriarch of female sex-hormones. It boosts our libido, increases our levels of happy hormones (serotonin and dopamine) and can boost our production of endorphins

So yeah—she’s a keeper. 

But like all of our hormones, if our oestrogen gets out of balance and we have too much or too little, it can cause a whole host of problems, including fertility issues. 

So let’s dig a little deeper and get to grips with what exactly does oestrogen do in the body? And how can it affect our fertility?

First up, what is oestrogen?

Oestrogen is an important hormone in people of all sexes. It’s generally known as the ‘female’ sex hormone, because of its role in the development of the female reproductive system and regulation of the menstrual cycle. 

Whilst it’s true that oestrogen plays a bigger role in those assigned-female-at-birth, in fact, everybody produces oestrogen, regardless of sex.

In those assigned-female-at-birth, there are three main types of oestrogen:

  • Oestrone (E1): This is mostly produced after menopause and is less potent than E2.
  • Oestradiol (E2): This is the most active and abundant form—and generally the one most people are talking about when they refer to oestrogen. E2 is made in the ovaries during our reproductive years (after puberty and before menopause) and plays a big role in regulating our menstrual cycle. E2 is the type we test for in our at-home Hormone and Fertility tests.
  • Oestriol (E3): Another less potent form of oestrogen that’s produced during pregnancy in the placenta.

Okay, but what does oestrogen do inside my body?

Oestrogen wears many hats—it helps to regulate our menstrual cycles, triggers the development of secondary sex characteristics like breasts and pubic hair, helps to maintain things like our skin’s moisture, our mood and even our bone and heart health. 

Let’s take a closer look at oestrogen throughout the menstrual cycle.

What is oestrogen’s role in the menstrual cycle?

Like all of our menstrual cycle hormones, our oestrogen levels fluctuate throughout each cycle..

During the first part of our cycles, the follicular phase, which lasts from day 1 of our periods until ovulation (when we release a mature egg), our oestrogen levels start off low but steadily increase. In this phase, our eggs are maturing in preparation for ovulation. Our eggs mature in our ovaries, in little sacs called follicles. These follicles make oestrogen, so whilst your eggs are maturing, your follicles steadily release this oestrogen—and it rises until it reaches a peak, just before we ovulate.

Because of oestrogen’s feel-good factors, just before and during ovulation is the time of the month when we’ll be killing it, feeling our most fierce and fabulous. This is the time to book that big presentation at work, go on that first date or really push it in your gym session.
This peak in oestrogen causes a surge of another hormone—luteinising hormone (LH), which triggers the release of a mature egg from one of our ovaries. (Read more about the signs of ovulation here).

After ovulation, oestrogen levels gradually drop and despite a small second wind around a week later, they continue to level off throughout the second stage of our menstrual cycles—the luteal phase.

At the end of our cycles, if the ovulated egg has not met a sperm and been fertilised, all of our menstrual cycle hormones, including oestrogen, drop-off to their baseline levels—triggering our periods. (Read more about menstrual cycle basics here).

If our oestrogen levels get off balance, it can disrupt the balance of our other menstrual cycle hormones—potentially impacting ovulation. 
No ovulation = no pregnancy. So if you’re trying to get pregnant, testing your oestrogen levels is really important for understanding your ovulation and general menstrual cycle health.

Does oestrogen decline with age?

In short, yes. 

Thanks to our wonderful ‘biological clocks’, as we age, our oestrogen levels gradually decline. This is because our number of egg cells decreases as we age and as a result, our follicles stop growing and producing as much oestradiol (E2). 

After menopause (when our periods stop completely), our E2 levels completely drop off, which is what causes the common low oestrogen menopausal symptoms like hot flushes, dry skin and mood swings. During perimenopause (the lead up to menopause), E2 levels fluctuate up and down which can also cause menopausal symptoms.

Declining oestrogen levels has whole-body knock-on effects, but luckily these days hormone replacement therapy (HRT) can be a great option to relieve symptoms for many people during perimenopause and post menopause.

How do I know if my oestrogen levels are normal?

Because our oestrogen levels fluctuate during our cycles, as we age and are dependent on whether we’re taking hormonal birth control or not, our ‘normal’ level is constantly changing. 

Like all of our hormones, our oestrogen is super sensitive and can easily get off balance. Oestrogen imbalances can cause a whole host of symptoms and can be caused by both lifestyle and genetic factors.

Oestrogen dominance is a phrase that has been used to describe a phenomenon when oestrogen levels are too high in relation to the other sex hormones in your body.  Although it’s not a clinically recognised term, being more sensitive or having excess oestrogen is known to cause symptoms like irregular periods, abnormal vaginal bleeding, bloating, swollen or tender breasts and weight gain. Some causes of high oestrogen levels include underlying health conditions, genetic factors, dietary and lifestyle factors, environmental pollutants. 
On the flip side, when oestrogen levels are too low we can experience irregular periods, fertility difficulties, reduced bone density, vaginal dryness, hot flushes and dry skin—to name a few. Having very low oestrogen levels can be caused by your ovaries not working properly, which occurs in menopause or premature ovarian insufficiency  (POI). However,  underlying health conditions like pituitary gland disorders, as well as having very low levels of body fat, a high caffeine intake, smoking and excessive exercise can also result in lower oestrogen levels.

Luckily, testing our E2 levels with a hormone test can help us to decipher if our oestrogen levels are within the normal range for us. 

Oestrogen FAQs

Where can I get an oestrogen blood test?

You’ve landed in the right place. With a Hertility Hormone and Fertility test you can get an accurate reading of your baseline E2 levels alongside other reproductive hormones. Your test will be sent straight to your door for you to do at-home and you’ll receive a doctor-written report along with your results. If your E2 levels come back out of range, you can arrange to chat with one of our doctors and we can support you with whatever treatments you may need. Jammy huh?

Can I get pregnant with high oestrogen levels?

Technically, yes. Although it can be harder as high oestrogen (which some people refer to as oestrogen dominance) can impact your fertility because of how it throws off your other menstrual cycle hormones. If you’re experiencing symptoms of oestrogen dominance it’s best to get your hormones tested before you try to conceive so you know where you’re at.  

How to boost oestrogen levels?

Firstly, the cause of low oestrogen levels must be identified. If you have not gone through menopause, have no underlying conditions and lead a healthy lifestyle but are struggling with low oestradiol symptoms, your doctor might suggest going on hormonal contraception to improve them.

Certain lifestyle factors like smoking, being underweight or exercising excessively can also cause lower levels of oestrogen.  If you’re going through perimenopause or gone through menopause, hormone replacement therapy (HRT) is an effective way to improve symptoms of low oestrogen. HRT comes in the  forms of topical gels, sprays, patches, pessaries and oral tablets. 

Are there natural oestrogen supplements?

If you’re looking to naturally boost oestrogen levels, have a look to see if there are any changes you can make to your lifestyle. Consuming a healthy, balanced diet (focusing on a Mediterranean diet can help), as well as cutting down on stress, smoking and excessive exercise are all things you could do to ensure your oestrogen levels are in check. 


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