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Follicle-stimulating hormone (FSH) does exactly what its name indicates. It helps stimulate the growth of ovarian follicles during your menstrual cycle.
As you age, it’s normal to see an increase in your FSH levels. This is because over time, the number of eggs you have naturally decreases. And this decline signals the pituitary gland to release more FSH in an effort to stimulate more follicle and egg growth.
But how can you know what’s considered “normal” FSH for your age? And when should you get your FSH levels tested?
We’ve done the research for you! Let’s dive into what high or low FSH levels could mean and check out our normal FSH levels by age chart for reference!
What is FSH?
FSH, aka follicle stimulating hormone, is secreted by the anterior pituitary gland in the brain. In females, the receptor for FSH is located on the granulosa cells of follicles. (A follicle is a sac that houses the reproductive cells that mature into an egg). The main job of FSH is to initiate the growth of your ovarian follicles so you have a mature egg to ovulate each month.
Here’s how it works:
- The hypothalamus, or the “headquarters,” gives the signal to release GnRH (gonadotropin-releasing hormone).
- Then the pituitary gland, or the “command center,” reacts to this by producing FSH.
- The release of FSH acts upon your ovaries and helps stimulate the growth of your follicles.
How does FSH affect fertility?
FSH plays a key role for both men and women. For men, FSH levels stay relatively constant. But for women, FSH levels fluctuate based on the stage of the menstrual cycle. Below is an even closer look at how FSH functions for each sex.
FSH in women
During the first half of the menstrual cycle (aka the follicular phase), FSH levels increase to promote the growth of ovarian follicles. Of the group of follicles naturally selected every month, one of them matures and releases an egg. We call this ovulation.
As you near ovulation, together FSH and LH create the final growth spurt needed to trigger egg release from the dominant follicle.
After ovulation, in the luteal phase, FSH production takes a bit of a breather. But during this time, it still plays a vital role by helping with the production of estrogen and progesterone.
FSH in men:
Follicle stimulating hormone has an important job for men too. In males, the receptor for FSH is located on the Sertoli cells that are responsible for sperm production. So FSH, along with testosterone, helps start and maintain sperm production.
Now that you’ve seen how FSH works, let’s understand what FSH values should look like for women.
What are normal FSH levels for women?
Your precise FSH values will depend on what phase of your menstrual cycle you’re in.
Here’s what serum FSH levels look like during different phases:
Phase of menstrual cycle | Serum FSH levels |
Follicular phase | 1.4 – 9.9 IU/mL |
Ovulatory peak | 6.2 – 17.2 IU/mL |
Luteal phase | 1.1 – 9.2 IU/mL |
After menopause | 19.3 – 100.6 IU/mL |
Know more: What do FSH Hormone Values Mean?
Normal FSH levels by age chart
As you saw in the previous chart, FSH levels fluctuate throughout your cycle. But remember that FSH levels change with age too.
So what is a good FSH level by age? Take a look at the table below:
Age (in years) | Mean FSH (IU/L) |
<35 | 6.5 ± 2.3 |
35-38 | 7.5 ± 2.4 |
38-40 years | 7.8 ± 2.5 |
>40 years | 8.5 ± 2.4 |
To better understand how these levels were determined, let’s review the research.
The study measured FSH and LH during the follicular and ovulation phase in a group of 560 women. Their baseline FSH levels were checked on cycle days 2 to 4. In the chart below, you’ll see the relationship between the women’s age and their baseline FSH levels.
Visually, you can see a steady upward trend in FSH levels from a woman’s late 20s through her mid-to-late 30s.
Then in the 35-36 age group and onwards, the increase in mean FSH levels is more noticeable. And once a woman passes age 40, FSH levels rise even more sharply. This time is referred to as the perimenopausal rise, and it’s a normal part of the aging process.
FSH also fluctuates throughout your cycle and factors into your peak fertility.
One study looked at the cycles of 50 women to see the role FSH played in the final egg maturation process. Their research showed that a surge in FSH alongside LH did indeed help with the final growth and release of the egg.
Essentially, this re-emphasizes how FSH and LH work closely together to orchestrate the menstrual cycle. But keep in mind that this study was relatively small, and exact FSH patterns will vary from woman to woman.
In the image below, you can see for yourself how LH and FSH rise and fall together.
At this point, you’ve seen how FSH changes over time and within a cycle. Now, let’s talk about why overall levels of this hormone increase as you get older.
Why does FSH increase with age?
Let’s nerd it out for a minute and understand why your FSH levels steadily increase with age.
Women are born with a fixed number of eggs. You start with about 2 million eggs at birth. By the time you reach puberty, that number drops to about 400,000. And from there, your total amount of eggs keeps naturally decreasing with time.
The number of follicles recruited every month also lessens as the number of eggs decreases. Since fewer follicles are growing, they secrete less estrogen. The brain senses this and tries to boost production by sending a stronger signal of FSH.
The bottom line of it all? A depletion in the egg reserve leads to less estrogen. The brain doesn’t get a signal from estrogen to reduce FSH production. Hence, FSH levels keep on increasing.
Know more: What Are My Chances of Getting Pregnant by Age? Check Out Our Chart
Now that you’ve seen why FSH increases with age, let’s learn how you can keep tabs on your current FSH levels.
How to know my FSH levels?
It’s a good option to get your FSH levels tested if you’ve been trying to conceive for a while with no success. Just remember that the numbers don’t tell the whole story of whether or not you can get pregnant.
One way to test your FSH levels is with an at-home testing kit or fertility monitor like the Inito monitor.
The Inito fertility monitor uses a single strip to test the levels of 4 different fertility hormones in your urine. These are LH, estrogen, PdG, and FSH. The best part? You’ll get exact values for each of these hormones.
Another way to check your FSH levels is through a simple blood test. Your healthcare provider may recommend this to you if you have irregular periods or no periods at all.
Based on your blood FSH results, your doctor may also order additional tests to get a better picture of your ovarian reserve. These include an AMH (Anti Mullerian Hormone) test and an AFC (Antral Follicle Count) test.
Let’s say you do get your FSH levels checked and they come back high. What then? We’ll go over the potential causes of high FSH next.
What if my FSH levels are too high?
If your test results indicate high FSH levels, there could be an underlying condition at play.
But try not to panic or self-diagnose. Instead, it’s best to visit your doctor to find out the root cause.
Here are some reasons your FSH levels may be high:
1. Perimenopause or menopause
High levels of FSH are a normal sign of perimenopause or menopause. This is because as
the number of eggs decreases, your brain release more FSH to trigger follicle growth.
Read more: Boost Your Ovarian Reserve: How to Reduce High FSH Levels
2. Primary ovarian insufficiency (POI)
High levels of FSH are also caused by Primary Ovarian Insufficiency (POI). This is when your ovaries stop working normally when you’re younger than 40.
You may experience menopause-like symptoms, and have irregular menstrual cycles. POI is caused by factors like genetics, illness, or trauma. Even in this case, the pituitary gland releases more FSH in an attempt to make your ovaries work.
3. Turner’s syndrome
Turner’s syndrome is a genetic condition associated with ovarian dysfunction, and in turn, high FSH levels.
With Turner’s syndrome, one of the X chromosomes is missing, partially or completely. Signs of this condition are delayed puberty, no periods, and features such as a webbed neck or low hairline at the base of the neck. It can also increase your risk of autoimmune disorders.
4. Pituitary or hypothalamic dysfunction or tumors
Some pituitary tumors (about 20%) are growth hormone-secreting adenomas. These types of tumors may secrete high levels of FSH followed by low levels of LH.
What if my FSH levels are too low?
It’s quite rare to have low FSH levels. Most commonly, low FSH indicates issues with the hypothalamus or the pituitary gland. This can lead to irregular or longer menstrual cycles since the ovaries don’t mature enough eggs to ovulate regularly.
Some reasons for low FSH levels include:
1. Problems with the hypothalamus or pituitary
If the hypothalamus doesn’t produce enough GnRH, the pituitary gland won’t receive the signal to produce enough FSH. At times, even tumors in the pituitary gland can grow, press on, and damage the pituitary tissue. This would mess with the gland’s ability to produce FSH.
2. Kallmans syndrome
Kallmans syndrome is a rare genetic disorder where there’s a delay or absence of puberty due to the deficiency of GnRH. The deficiency in this hormone then leads to a deficiency in FSH.
Other indicators of this syndrome are:1) a lack of sexual maturation during puberty 2) no periods (amenorrhea), and 3) other features such as impaired sense of smell, cleft lip, or color blindness.
3. Being severely underweight or having recent rapid weight loss
Either of these conditions can disrupt the hormonal balance including lower GnRH, and hence lower FSH levels.
Will high or low FSH levels affect my chances of getting pregnant?
Remember that your FSH levels (high or low) are not the root issue. FSH can help indicate the presence of an underlying issue. But FSH levels on their own do not tell the whole picture of your ability to get pregnant.
That’s why it’s best to consult a doctor if you have concerns with your FSH. They can help you address any underlying issues that may be a barrier on your journey to conception.
Getting pregnant with high FSH levels
If you have trouble conceiving due to high FSH levels, these treatments may help:
- Fertility medications such as gonadotropins: This is often recommended for women with irregular or no periods. You may also be recommended other fertility medications such as letrozole or clomiphene before gonadotropins. When conceiving naturally, this can help you start ovulation and track your fertility window.
- In vitro fertilization (IVF) or Intrauterine insemination (IUI): These assisted reproductive technologies also use gonadotropins or medications that use synthetic FSH. These medications trigger the ovaries to produce more than one follicle for the month.
- Lifestyle changes: Certain lifestyle factors can affect your body’s hormonal balance. Exercising regularly, maintaining a healthy diet, getting enough sleep, and managing stress can help regulate your hormones including FSH. When your hormones are balanced, your chances of conceiving are better.
- Donor eggs: In cases of declined ovarian reserve, you may not be able to produce enough quality eggs to get pregnant. If this is the case, you may choose to use donor eggs. One study found that donor eggs can significantly increase your IVF success rate, especially for women above 40. You can see the donor egg IVF success rates below.
Getting pregnant with low FSH levels
Again, low FSH is much less common. But treatment options for low FSH levels include:
- Medication, such as hormone replacement therapy: This works to correct the deficiency of hormones such as FSH, LH, and estrogen. And ultimately, this restored balance helps stimulate the ovaries to produce eggs.
- Surgery: If a pituitary tumor is affecting hormone production and medication hasn’t helped, the tumor can be removed surgically.
Of course, knowing your FSH levels is the first step of your journey to conception. If your levels are normal, that’s great! If not, talk to your doctor to figure out a personalized plan.
Takeaways
- FSH is a key fertility hormone for men and women.
- FSH levels in women fluctuate based on the stage of the menstrual cycle. They rise during the follicular phase and ovulation and drop during the luteal phase.
- FSH levels increase with age as the egg reserve depletes naturally.
- Having high FSH or low FSH can help assess your ovarian reserve. But FSH alone isn’t a direct indicator of your chances of getting pregnant.
- It’s more common to have high FSH. The possible causes are perimenopause, POI, and Turner’s syndrome.
- It’s less common to have low FSH. But low FSH is caused by pituitary tumors, Kallman’s syndrome, being severely underweight, or having rapid weight loss.
- Addressing the root cause for low FSH or high FSH is the first line of treatment when trying to conceive.
FAQs
Typical blood FSH levels by age can look like:
- Before puberty: 0 to 4.0 mIU/mL (0 to 4.0 IU/L)
- During puberty: 0.3 to 10.0 mIU/mL (0.3 to 10.0 IU/L)
- Women who are still menstruating: 4.7 to 21.5 mIU/mL (4.5 to 21.5 IU/L)
- After menopause: 25.8 to 134.8 mIU/mL (25.8 to 134.8 IU/L)
Serum FSH levels can vary depending on the laboratory and the values they use. But generally, 19.3 – 100.6 IU/mL or 8.5 ± 2.4 IU/L in women is considered to indicate menopause.
Levels of FSH might vary based on clinics and the assessments they use. So technically, there’s no such thing as a “bad FSH level.” And remember, that FSH on its own is not the issue. So more testing may be necessary to see if there’s a deeper condition that needs attention.
The symptoms of low FSH depend on the underlying cause. But lengthened or irregular menstrual cycles, vaginal dryness, and infertility may be present.
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- FSH may be a useful tool to allow early diagnosis of Turner syndrome
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