FSH 101: What Do Low And High Levels Mean?

FSH 101: What Do Low And High Levels Mean?

In the fertility healthcare lexicon, it’s understandable that the abbreviation ‘FSH’ doesn’t enter it until we’re planning for a family. However, it’s a crucial hormone that you need to learn about ASAP. 

Pop quiz: how many hormones exist in our bodies? If your answer is ‘over 50’, please thank Google-sensei for teaching you a new fun fact. There are indeed that many different chemical substances in our blood stream [1]! Each hormone serves a different purpose as well, so you’d be hard-pressed to remember every single one of them if you aren’t a medical doctor.

On the other hand, there are hormones that you’ve probably read about fairly frequently. Take insulin for example. This hormone is often mentioned alongside diabetes, given that it's a disease that either does not use insulin efficiently or simply doesn’t produce enough of it [2].

Then, there’s testosterone. It’s a male sex hormone, and anabolic steroids (yes, those) are synthetic derivatives of it [3].

When it comes to female fertility, there are several hormones that you need to take note of. These include progesterone, estradiol, luteinising hormone (LH), and follicle-stimulating hormone (FSH). Regarding the latter hormone, you don’t see it being mentioned often, but you’d do well to know more about it when you’re trying to conceive (TTC). Here’s why.


What is FSH?

FSH is a hormone that’s produced by the pituitary gland, located at the bottom of your brain below the hypothalamus [4]. FSH aids in controlling your menstrual cycle and stimulates egg growth in the ovaries [5]. As you might expect, your FSH levels are at their highest during ovulation.

What you might not expect would be that FSH is important for males too, stimulating the testes to produce sperm [6]. For the most part, males do not experience drastic shifts in their FSH levels throughout life. However, abnormal FSH levels in males might be an indicator of infertility because of how crucial this hormone is to sperm production [7].

To determine your FSH levels, you’ll need to take a blood test at a clinic or hospital [8]. These days, there are also FSH tests that you can purchase off the shelf, allowing you to observe your FSH levels in full privacy and comfort.

One example would be twoplus Fertility’s own FSH Hormone Test Kit for women, which tests for a total of 5 hormones, including FSH.

Normal FSH levels for men and women

Many things can affect one’s FSH levels, even for males. As a point of reference, the tables below detail normal FSH levels for men, pregnant women, and women who are not pregnant [9]. These are all expressed in International Units Per Litre (IU/L).


Life Stage

FSH Range (IU/L)

Before Puberty

0 - 5

During Puberty

0.3 - 10


1.5 - 12.4

Women (Not Pregnant)

Life Stage

FSH Range (IU/L)

Before Puberty

0 - 4

During Puberty

0.3 - 10

During Menstruating Years

4.7 - 21.5


25.8 - 134.8

Women (Pregnant)

Pregnancy Stage

FSH Range (IU/L)

First Trimester

0.1 - 18.3

Second Trimester

3 - 10

Third Trimester

3 - 10

Now that you have these figures on hand, it’s time to discover what can affect an individual’s FSH levels.


What affects one’s FSH levels?

There are 2 clear indicators from the tables above, and they would be age and gender. This is especially pronounced in women, whose FSH levels are at their highest after menopause. For ladies who are still menstruating, FSH levels fluctuate across the different phases. The mid-cycle stage of menstruation has the highest FSH levels, peaking at 26 IU/L [10].

Chronic high stress negatively impacts FSH levels too, essentially stopping the pituitary gland from creating and releasing FSH and LH [11]. There’s also the nasty side effect of having a lowered sex drive, which serves as a coup de grâce for family planning. Hence, couples who are TTC should pay special attention to their stress levels and carve out sufficient time to rest and relax.

Certain drugs can affect your FSH levels as well. For example, digitalis and levodopa can raise your FSH levels while certain birth control pills can lower them instead [12]. These might skew the results of your FSH test, so do inform your doctor if you’re on any medication that has the potential to influence your FSH levels.


What do high FSH levels mean?

For children, it’s a sign that puberty is about to begin. For males on the other hand, high FSH levels are an indicator of damaged or non-functioning testicles [13]. For women who aren’t pregnant, high FSH values can indicate premature menopause or a poor ovarian reserve [14]. These are damaging health conditions for women who are TTC.

Premature menopause is fairly self-explanatory, referring to women who experience menopause before they’re 40 years old [15]. Their ovaries stop producing and releasing eggs, and they’ll have a longer postmenopausal life compared to other women. Additionally, there’s also the immense emotional toll that the diagnosis may take on them.

A poor ovarian reserve refers to a woman having an abnormally diminished supply of eggs [16]. Although it’s still possible to conceive, the chances are definitely lower than women who have an optimal ovarian reserve. Getting diagnosed with this health condition early is the best cure for couples who are TTC.


What do low FSH levels mean?

Akin to having high FSH levels, the significance of low FSH levels largely depends on your age and gender. As shown in the tables above, it’s normal for males and children to have lower FSH levels. Ditto for women who are pregnant. However, women who aren’t pregnant need to sound the alarm if their FSH values are abnormally low.

For one, it can indicate that your ovaries are not maturing enough eggs and this will impact your fertility [17]. 

However, what’s more concerning would be that low FSH levels can indicate a person is suffering from an energy deficiency. This can be attributed to an eating disorder like bulimia nervosa [18], which also results in infertility and menstruation problems. Individuals suffering from this but are of a normal weight or slightly overweight can appear as if nothing is wrong. However, their hormone levels are still negatively impacted. 


How does FSH affect pregnancy?

FSH plays an important role throughout your fertility journey. When you’re TTC, your body needs to balance its FSH levels because abnormally high or rock bottom values will either disrupt ovulation or indicate potential fertility issues [19]. The ideal FSH level for women who are TTC would be below 10 IU/L.

Apart from that, heave a sigh of relief because FSH levels are expected to be low throughout pregnancy as the hormone’s job is already done [20]. Recall that its main role is to stimulate egg growth and control your menstrual cycle — these aren’t exactly going to happen while you’re pregnant.

And if you have elevated FSH levels while you’re TTC, it’s more difficult but definitely not impossible [21]. Once you successfully conceive, don’t worry about your FSH levels. They will drop and normalise at a range of 3 IU/L to 10 IU/L from your second trimester onwards.


In closing

So many hormones, so little time. It’s a superhuman feat to remember the names and responsibilities of all the chemical substances running through our body, but they’re all paramount to our survival. FSH for one, is a key hormone that indicates how fertile you are and alerts you to the presence of other health issues. This applies to men as well.

Therefore, you should take a comprehensive hormone test when you’re TTC. The information will help you, your partner and your gynaecologist plan ahead. FSH might be just 1 hormone that affects your fertility, but as you can see, it’s clearly an important one. This is an abbreviation that won’t be disappearing from your vocabulary anytime soon.

[1] United States Environmental Protection Agency, What Is The Endocrine System?, https://www.epa.gov/endocrine-disruption/what-endocrine-system
[2] U.S. Department of Health & Human Services, What is Diabetes?, https://www.cdc.gov/diabetes/basics/diabetes.html
[3] Kavitha Ganesan, Sajedur Rahman, Patrick M. Zito, Anabolic Steroids, https://www.ncbi.nlm.nih.gov/books/NBK482418/
[4] Cleveland Clinic, Pituitary Gland, https://my.clevelandclinic.org/health/body/21459-pituitary-gland
[5] U.S. Department Of Health And Human Services, Follicle-Stimulating Hormone (FSH) Levels Test, https://medlineplus.gov/lab-tests/follicle-stimulating-hormone-fsh-levels-test/
[6] National Cancer Institute, FSH, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/fsh
[7] Path Fertility, FSH Levels In Men And Why It Matters For Fertility, https://pathfertility.com/fsh-levels-in-men-and-why-it-matters/
[8] Dotdash Media, Inc., Here's Why An FSH Test Is Important For Monitoring Your Fertility, https://www.verywellfamily.com/day-3-fsh-levels-test-1960172
[9] Icahn School Of Medicine At Mount Sinai, Follicle-Stimulating Hormone (FSH) Blood Test, https://www.mountsinai.org/health-library/tests/follicle-stimulating-hormone-fsh-blood-test
[10] Healthline Media UK Ltd, What Are Normal Ranges Of FSH Levels, And What To Do If They Are High Or Low, https://www.medicalnewstoday.com/articles/317746
[11] Designs For Health, Does Stress Affect Fertility?, https://blog.designsforhealth.com/node/808
[12] WebMD LLC, What Is A FSH Test?, https://www.webmd.com/women/fsh-test
[13] Healthline Media, Follicle-Stimulating Hormone (FSH) Test, https://www.healthline.com/health/fsh
[14] Progyny, Inc., Is High FSH The Same As Menopause?, https://progyny.com/education/female-infertility/high-fsh-menopause/
[15] Department Of Health, State Government Of Victoria, Australia, Premature And Early Menopause, https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/premature-and-early-menopause
[16] Healthline Media, What Is Diminished Ovarian Reserve And What Can You Do About It?, https://www.healthline.com/health/diminished-ovarian-reserve
[17] Hertility Health Limited, Follicle-Stimulating Hormone: What Do Your FSH Levels Mean?, https://hertilityhealth.com/blog/what-do-your-fsh-levels-mean/
[18] Resch et al., Eating Disorders From A Gynecologic And Endocrinologic View: Hormonal Changes, https://www.fertstert.org/article/S0015-0282(03)03191-1/pdf
[19] American Pregnancy Association, How Do FSH Levels Affect Fertility?, https://americanpregnancy.org/getting-pregnant/infertility/how-does-fsh-levels-affect-fertility/
[20] Modern Fertility, What's Happening To Your Hormones In Early Pregnancy?, https://modernfertility.com/blog/hcg-levels-hormones-early-pregnancy/
[21] HowStuffWorks, How Do High FSH Levels Affect Getting Pregnant?, https://health.howstuffworks.com/pregnancy-and-parenting/pregnancy/fertility/how-do-high-fsh-levels-affect-getting-pregnant.htm