It’s blamed for PMS, fibroids, and more — but oestrogen is actually essential for almost every system in your body. Here’s what it really does.
Oestrogen gets a lot of bad press. It’s often linked to PMS, endometriosis, fibroids, and even breast cancer. But blaming one hormone for all of that is a bit like blaming the weather forecast for the storm — it’s more complicated than that.
The truth is, oestrogen is not the villain. It’s a vital hormone that keeps your bones strong, your heart healthy, your brain sharp, and your mood stable. When it’s in balance, it works quietly and brilliantly behind the scenes. Problems tend to arise when there’s too much or too little — not simply because it exists.
So let’s give oestrogen a proper introduction.
What Is Oestrogen?
“Oestrogen” isn’t just one hormone — it’s actually a family of hormones. There are four main types, and each one plays a different role depending on your life stage:
- Oestradiol (E2): The most powerful form. This is the main oestrogen in women who are still having periods. It does most of the heavy lifting — from regulating your cycle to supporting your bones and brain.
- Oestrone (E1): A weaker form, produced mainly in fat tissue. It becomes the dominant type after menopause, when the ovaries slow down.
- Oestriol (E3): The mildest form. Its moment to shine is during pregnancy, when it rises significantly to support the growing baby.
- Estetrol (E4): A pregnancy-only oestrogen, made by the baby’s liver. It’s still being studied, but it’s thought to play a protective role.
The type of oestrogen your body relies on most changes throughout your life — this is completely normal and by design.
Where Does Oestrogen Come From?
This depends on where you are in your hormonal journey.
Before Menopause
Your ovaries do most of the work. They produce oestradiol (E2) in a rhythm that rises and falls with your menstrual cycle — peaking before ovulation, then again in the second half of your cycle.
After Menopause
When the ovaries retire from producing large amounts of oestrogen, the body doesn’t just switch off — it adapts. Three backup systems take over, producing smaller amounts of weaker oestrogen:
- Fat tissue (adipose tissue): This becomes the main source post-menopause. Fat cells contain an enzyme called aromatase, which converts hormones made by the adrenal glands (called androgens) into oestrone (E1). This is one reason why body composition can affect hormonal health after menopause.
- Adrenal glands: These small glands (sitting on top of your kidneys) produce precursor hormones like DHEA and androstenedione. These get converted into oestrogen by tissues around the body. Think of the adrenals as the suppliers, and the tissues as the factories.
- Skin, bones, and muscles: These tissues also carry aromatase and can convert androgens into small amounts of local oestrogen. The quantities are modest, but they can have a meaningful effect right where they’re produced.
After menopause, your body doesn’t stop making oestrogen entirely — it just makes less, in different places. Supporting your adrenals and maintaining a healthy body composition can make a real difference to how you feel.
How Much Oestrogen Do You Make?
Oestrogen levels naturally shift a lot throughout life. Here’s a rough guide:
- Follicular phase (before ovulation): 200–500 pg/mL
- Luteal phase (after ovulation): 40–200 pg/mL
- Postmenopause: Less than 30 pg/mL
That’s a dramatic drop — and it explains why menopause can feel so significant. Oestrogen touches almost every system in your body, so when levels fall sharply, the effects are felt widely.
What Does Oestrogen Actually Do?
Oestrogen is involved in far more than just your reproductive system. Here’s a plain-English look at its reach:
- Reproductive health: Regulates your menstrual cycle, supports fertility, and prepares the uterus lining each month.
- Bone health: Helps maintain bone density. When oestrogen drops after menopause, bone loss can accelerate — which is why osteoporosis is more common in women.
- Heart health: Supports the flexibility of blood vessels and helps maintain healthy cholesterol levels. This is partly why women’s risk of heart disease rises after menopause.
- Brain health: Influences mood, memory, and concentration. Many women notice brain fog or low mood when oestrogen dips.
- Skin health: Helps skin stay hydrated and elastic. Declining oestrogen is one reason skin changes texture and loses firmness with age.
- Gut health: Plays a role in shaping the gut microbiome and how food moves through the digestive system.
- Immune health: Modulates how the immune system responds, which is one reason autoimmune conditions are more common in women.
Oestrogen isn’t just a “sex hormone” — it’s a whole-body hormone. Its influence stretches from your joints to your jaw, your gut to your brain.
Signs That Oestrogen May Be Out of Balance
Because oestrogen affects so many systems, an imbalance — in either direction — can show up in a wide variety of ways.
Signs of Too Much Oestrogen
- Breast swelling or tenderness
- Heavy periods with clots
- Mood swings and irritability
- Water retention and bloating
- Weight gain around the hips and thighs
- Fibroids or polyps
- Histamine-type symptoms: headaches, itchy skin, or allergies
Signs of Too Little Oestrogen
- Hot flushes and night sweats
- Low mood, anxiety, or depression
- Vaginal dryness & Low libido
- Bone loss (osteopenia or osteoporosis)
- Joint pain
- Brain fog or poor concentration
- Weight gain around the abdomen
If you recognise yourself in either list, it’s worth speaking to a healthcare professional. Hormonal symptoms are real and manageable — you don’t have to just put up with them.
The Takeaway
Oestrogen isn’t something to fear. It’s a hormone your body genuinely needs — at every age and stage of life. The goal isn’t to eliminate it; it’s to understand it, support it, and keep it in healthy balance.
When you know what oestrogen does and what throws it off course, you’re in a much better position to take care of your health — and to advocate for yourself when something doesn’t feel right.
Knowledge is the first step. You’ve got this.