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Maybe you’ve taken an FSH blood test at home, or perhaps it was part of a bigger fertility workup with your doctor. Just like with any test, it’s natural to want to know anything and everything about the FSH before you get poked or prodded. That’s what we’re here for.

What is the FSH blood test?

FSH stands for follicle stimulating hormone—it’s the hormone that (you guessed it) stimulates follicles in the ovaries to grow into eggs each month. This process is necessary for a woman to ovulate each month and for conception to happen naturally. The FSH blood test measures the levels of FSH around day three of your menstrual cycle to see if all looks normal. In turn, it gives doctors a sense of a woman’s ovarian reserves, says Dr. Spencer Richlin, MD, partner and surgical director at Reproductive Medicine Associates of Connecticut (RMACT).

Ovarian reserves are important in fertility evaluation, since women are born with only a finite number of eggs, and with age, the amount and quality of eggs is known to decline, says Dr. Richlin. This could cause problems getting pregnant—but don’t panic. Taking an FSH blood test is one of the first steps to figuring out any problems with your reproductive endocrinologist and (hopefully) getting on a path to a solution. 

Why am I getting an FSH Test?

The FSH is a common test for women who’ve been trying to conceive for a while unsuccessfully and seek help from a fertility doctor. It is given as part of a patient’s reproductive evaluation. 

But the FSH is not a standalone test. You’ll probably get it in conjunction with several other fertility tests for you and for your partner, if you have one. In addition to FSH testing, your doctor might suggest an ultrasound of your ovaries, a semen analysis, and potentially an HSG (hysterosalpingogram, a specialized X-ray to make sure fallopian tubes aren’t blocked).

Your blood may also be tested for other hormones, including:

  • Anti-Mullerian Hormone (AMH): This level can be tested at any time during the menstrual cycle. AMH is secreted by the follicles and is correlated with the number and quality of remaining eggs.
  • Luteinizing Hormone (LH): High levels of this hormone are associated with ovarian failure and polycystic ovary syndrome (PCOS), which can affect a woman’s ability to get pregnant.
  • Estradiol: A normal level of this form of estrogen is a sign the ovaries are working properly.

 Even if you’re not quite ready to have a baby, the FSH blood test can help you understand your ovarian reserve, especially if you’re considering freezing your eggs one day. 

What can I expect during the FSH blood test?

The key to FSH blood testing is timing: Because follicle stimulation occurs in the beginning of the menstrual cycle, you must have your blood drawn at day 2, 3 or 4 of your menstrual cycle—understanding that the first day of your period is considered day 1. Other than getting the timing correct, there’s nothing else you need to do to prep.

The blood test is simple and much like a blood draw you’d get for a physical exam. The nurse will take a blood sample using a needle, and it will be sent to a lab for analysis.

On the same day, you’ll probably also have a transvaginal ultrasound, where the doctor will count the number of follicles—a.k.a. future eggs—in your ovaries. Your follicle count will predict how you might do if your ovaries get stimulated as part of an IUI or IVF process. Eliminating all other factors, the higher the follicle count, the better patients might do.

What do the FSH blood test results mean?

The FSH blood test results will come back as a level of FSH in the blood in milli-international units per milliliter (mlU/ML). To understand your FSH test result, remember that generally, a lower number is better—meaning the lower the FSH, the greater the ovarian reserve.

Here’s a general guide to what FSH levels can mean:

  • Below 10 mIU/ML is considered normal.
  • 10-15 mIU/ML is a “gray area,” says Dr. Richlin.
  • Above 15 mIU/ML is associated with a diminished ovarian reserve.

But know that the FSH level alone doesn’t give doctors a full picture of your ability to get pregnant. Other factors might be at play, and, according to Dr. Richlin, “FSH is only one piece of the reproductive puzzle that we use to help us counsel our patients.”

What happens next?

With the results of the FSH test, along with the battery of other tests you’ll get (hang in there!), your doctor will counsel you on the next steps that are right for you.

For example, if your FSH levels are normal, but you have another issue—such as a partner with a low sperm count or a uterine problem—then the other issue would need to be addressed in your fertility journey.

Plus, a high FSH level doesn’t mean you won’t conceive. It just means your doctor may recommend a quicker course of action that will help you make the most of the eggs you have left. For example, some women may decide to skip treatments that can take longer and go straight to IVF, where eggs are retrieved from the ovaries—often, several eggs at one time—and fertilized in the lab.

The FSH test is just an indicator, and doesn’t necessarily predict your outcome or whether you’ll become pregnant. If you have a higher FSH, you just might have to be more aggressive with your treatment and timeline. We’ll be here cheering you on.