Follicle-Stimulating Hormone: What Do Your FSH Levels Mean?

June 20, 2023Bríd Ní Dhonnabháin

FSH stands for Follicle-Stimulating Hormone and is one of the main hormones involved in the regulation of your menstrual cycle and ovulation—making it an important hormone not only for your health but your fertility too.

In this article we’re giving you the lowdown on everything you need to know about your FSH levels, including how to know what normal FSH levels look like, symptoms of high and low FSH levels and how to balance your FSH levels.

  1. What is FSH?
  2. What are normal FSH levels in women?
  3. What does FSH do?
  4. High FSH levels
  5. Low FSH levels
  6. Hormone test for FSH levels

What is FSH? 

FSH is what’s known as a gonadotropin hormone. It’s released by the pituitary gland in the brain and then acts on the ovaries.

There is only one other gonadotropin hormone in the body—luteinising hormone (LH). True partners in crime, there’s no FSH without LH, and they act in tandem to bring about changes which essentially regulate ovulation.

Normal FSH levels in women

Because our FSH levels are intricately linked to our ovarian reserve (more on this later) , what’s considered a ‘normal’ FSH level changes as we age. This is because our ovarian reserve declines as we age which makes our FSH levels increase. 

Gonadotropic hormones are hormones released from the pituitary gland in the brain and released into the bloodstream. Gonadotropins then go on to act on the ovaries. There are two types of gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The pituitary gland produces FSH which acts on the ovaries to stimulate the growth of follicles containing your eggs. As well as growing the ovarian follicles, FSH stimulates the granulosa cells that surround the follicle to produce oestrogen, an essential hormone for regulating the menstrual cycle (1). You can read more about oestrogen here. 

What does FSH do?

FSH has two primary functions: 

  1. Help the follicles grow
  2. Help make oestrogen 

Follicular development

FSH does pretty much exactly what it says on the tin—it stimulates the growth of follicles which contain your eggs. 

You’re born with ‘immature’ eggs. So each month, a number of them start maturing before one is released during ovulation. Your eggs are housed in tiny follicles inside your ovaries, and it’s these follicles that FSH signals to to prepare your eggs for ovulation (2).

Oestrogen production

FSH also stimulates the cells that surround the follicles to make oestrogen, another essential hormone for regulating the menstrual cycle and reproductive health (1).

The relationship between FSH and LH

When your eggs are fully mature and ready to be released during ovulation, LH steps in. 

A surge of LH is released, again by the pituitary gland in the brain, causes the most mature follicle to rupture—releasing an egg into your Fallopian tube. This is ovulation. Despite FSH causing numerous follicles, and therefore numerous eggs, to mature each cycle, only one follicle will release an egg each month. This is because FSH and LH are both involved in negative feedback loops, controlled by E2. 

But what does negative feedback loop mean?

Increasing FSH levels in the early stages of your menstrual cycle leads to more oestrogen being made, but this has,a negative feedback effect on FSH levels. In other words, when you have lots of oestrogen, it feeds back to brain that it needs to stop making more FSH.

Similarly with LH, oestrogen levels keep increasing through the cycle and once they reach a peak around the middle of the cycle, it causes the sudden surge in LH that promotes ovulation.

After ovulation, the empty follicle that once contained the egg makes another hormone progesterone to support conception, implantation and the early stages of pregnancy.

High levels of progesterone tell the brain to stop making more FSH. Now if a pregnancy doesn’t happen, there is a drop in oestrogen and progesterone which not only triggers your period, but also tells the brain it needs to start making FSH to start the whole process all over again in the next menstrual cycle (5). 

High FSH levels

Okay, but what happens when we have low FSH levels? Let’s take a look at causes and symptoms of low FSH levels.

What causes high FSH levels?

The most common reason for high FSH levels is a low ovarian reserve (egg count), or ovaries that aren’t functioning properly.

When we have a low ovarian reserve, this essentially means we have a smaller number of immature follicles available in our ovaries and our bodies will produce less oestrogen. Because oestrogen controls how much FSH we produce (remember that negative feedback loop), when we have less oestrogen, our FSH levels may go up. 

High FSH levels can therefore indicate that our ovaries aren’t functioning properly, be an indicator of low ovarian reserve or an indicator of the onset of menopause.

Other reasons for high FSH levels can be ovarian cancer (although this is very rare) (9) and Premature Ovarian Insufficiency (POI) which is the loss of ovarian function before the age of 40 (6,7).

In some cases, dietary and lifestyle factors can moderately raise FSH levels. 

Symptoms of high FSH levels

Symptoms of high FSH levels usually mimic those of menopause and are related to low oestradiol levels —which is why it’s so important to test a range of your reproductive hormones to get to the bottom of symptoms. 

Symptoms can include:

  • Irregular periods or no periods
  • Hot flashes and/or night sweats
  • Skin and hair changes
  • Difficulty conceiving

How to lower FSH levels?

It is important to understand that if high FSH levels have been caused by menopause or a low egg reserve, modifications to your diet or lifestyle will not be able to reverse this.

However, there are some dietary lifestyle factors associated with a higher FSH, such as smoking and high alcohol consumption. 

If you’re trying to conceive, consider cutting alcohol and cigarettes completely as this will improve your chances of conception and prevent harmful effects to the baby during pregnancy (17).

For advice on how to quit smoking, see the full list of NHS quit smoking services here.

Nutrition can be a really powerful tool in balancing hormones and helping to alleviate symptoms. You can book a nutritional health consultation with one of our registered nutritionists via your health hub.

Low FSH levels

What do low FSH levels mean? 

Commonly, low FSH levels can be caused by the pituitary gland in the brain not functioning properly. This is also known as hypopituitarism.

Problems with the pituitary gland can be directly related to the gland itself, or with the hypothalamus—another part of the brain that controls the release of FSH. This can result in a disorder known as hypogonadotropic hypogonadism.

This can be caused by high levels of stress or an energy deficiency i.e. burning more calories than we are taking in through our diet. It can therefore be common in people who are very underweight, such as those who suffer from eating disorders, or who exercise excessively.  This can eventually result in your periods stopping, which is a condition known as hypothalamic amenorrhea.

Other less common causes of low FSH levels include glucocorticoids or meningitis. 

Symptoms of low FSH levels

Symptoms of low FSH can include:

  • Low sex drive
  • Fatigue
  • Infertility
  • Hot flashes
  • Irregular periods or no periods

Low FSH levels can mean that our ovaries are not maturing enough eggs. But again, symptoms can mimic symptoms from lots of other conditions, so testing a range of different reproductive hormones is important in order to get a clearer idea of what’s going on. 

How to increase FSH levels?

Diet and lifestyle changes can only improve FSH levels—but only if the root cause of low FSH levels are linked to diet or lifestyle factors.

If you think you could be in an energy deficiency, balancing your energy intake could improve your FSH levels, in addition to reducing any excessive exercise.

You can read more about the relationship between exercise and fertility and how much exercise is too much here

Find out more about your FSH levels

FSH is a vital hormone for regulating the menstrual cycle and ovulation. Doing a hormone blood test, like our Hormone & Fertility Test, is the only way to accurately determine your FSH levels. 

If you’re concerned about your FSH levels and would like to speak to someone, we recommend booking a consultation with one of our doctors or nutritional health specialists.

Key takeaways

  1. Follicle-stimulating hormone, or FSH, is a hormone made in the brain that acts on the ovaries and helps to regulate the menstrual cycle and ovulation
  1. FSH plays an important role in the growth of ovarian follicles (or eggs) and the production of oestradiol (E2)
  2. Normal levels of FSH in women change as we age and whether we are pre, peri or postmenopausal
  1. FSH is regulated by other hormones, including E2 and progesterone, acting on the hypothalamus to either increase or decrease FSH production
  2. High FSH levels can indicate premature ovarian insufficiency (POI), the menopausal transition. FSH levels can also be higher in heavy smokers or drinkers or people with a vitamin D deficiency. 
  1. Low FSH levels can mean your hypothalamus or your pituitary gland aren’t working as they should. This can be caused by stress or energy deficiency.
  1. Find out more about your FSH levels with an at-home Hormone & Fertility Test


  1. Follicle stimulating hormone 
  2. Physiology, Follicle Stimulating Hormone – StatPearls – NCBI Bookshelf 
  3. The Normal Menstrual Cycle and the Control of Ovulation 
  4. Luteinizing hormone and follicle stimulating hormone synergy: A review of role in controlled ovarian hyper-stimulation 
  5. Stimulatory and inhibitory effects of progesterone on FSH secretion by the anterior pituitary 
  6. Primary ovarian insufficiency: an update 
  7. Idiopathic primary ovarian insufficiency: a study of serial hormonal profiles to assess ovarian follicular activity
  8. FSH may be a useful tool to allow early diagnosis of Turner syndrome
  9. FSH and LH serum/tumor fluid ratios and malignant tumors of the ovary.
  10. Follicle-stimulating hormone concentrations in relation to active and passive smoking
  11. Smoking, alcohol and caffeine in relation to ovarian age during the reproductive years
  12. Ovarian function and cigarette smoking in the BioCycle Study 
  13. Alcohol intake induces diminished ovarian reserve in childbearing age women – Li – 2013 – Journal of Obstetrics and Gynaecology Research – Wiley Online Library 
  14. Association between serum 25-hydroxyvitamin D and ovarian reserve in pre-menopausal women 
  15. Is the ovarian reserve influenced by vitamin D deficiency and the dress code in an infertile Iranian population? 
  16. Persistent organic pollutants as predictors of increased FSH:LH ratio in naturally cycling, reproductive age women 
  17. Preconception care: caffeine, smoking, alcohol, drugs and other environmental chemical/radiation exposure 
  18. Effects of soy protein and isoflavones on circulating hormone concentrations in pre- and post-menopausal women: a systematic review and meta-analysis 
  19. Effects of soy foods on ovarian function in premenopausal women 
  20. Glucocorticoids, Stress, and Fertility 
  21. Eating disorders from a gynecologic and endocrinologic view: hormonal changes 
  22. Obstetric and gynecologic problems associated with eating disorders 
  23. A review of the pathophysiology of functional hypothalamic amenorrhoea in women subject to psychological stress, disordered eating, excessive exercise or a combination of these factors 
  24. Effect of Exercise on Ovulation: A Systematic Review 
  25. Prospective investigation of pituitary functions in patients with acute infectious meningitis 
  26. Hypothalamic pituitary dysfunction in acute nonmycobacterial infections of central nervous system 

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