FSH: Many of us know of it as it relates to a menstrual cycle, but what role does it play, exactly? Follicle-stimulating hormone, or FSH, is produced by the pituitary gland in the brain and not only initiates follicular recruitment during the menstrual cycle, but also promotes follicular growth, or ovarian stimulation, leading up to the releasing of an egg by the ovaries during ovulation. 

In a typical fertility workup, FSH is one of the hormones evaluated to help determine a woman’s ovarian reserve or the number of eggs remaining in the ovaries. 

To better break this all down for you, we spoke with Dr. Tamar Matitashvili, a leading fertility specialist at Dominion Fertility, where she dedicates herself to connecting with and helping her patients to grow their families. Now let’s dive in! 

High FSH: What does it mean?

“A woman’s FSH levels fluctuate during her menstrual cycle. They are relatively low at the beginning of the period and then go up to stimulate the ovary to develop a dominant follicle that will ovulate in mid-cycle,” explains Dr. Matitashvili. 

As the follicle grows, it produces estrogen that inhibits FSH release from the pituitary gland. FSH is also suppressed by Inhibin B, a hormone produced by small-sized follicles. 

For women experiencing fertility challenges, high FSH can be related to premature ovarian failure or a decreasing number of follicles that will help us predict how patients may respond to ovarian stimulation. Decreased ovarian reserve is associated with advanced maternal age but in young women can also be caused by different types of cancer treatments, a number of autoimmune disorders, as well as specific genetic causes.

FSH levels increase with age and are highest when women reach menopause. This is because, as women age, the number of follicles in their ovaries declines, as does the level of Inhibin B. This causes FSH production to increase — particularly during the late luteal and early follicular phases of the menstrual cycle. 

“FSH should be measured at the beginning of the follicular phase on menstrual days 2, 3, or 4 and measured with estrogen levels to help with the correct interpretation of its value. High FSH levels measured at the beginning of a woman’s menstrual cycle indicate a diminished ovarian reserve, meaning that the number of remaining eggs in the ovary is decreasing,” says Dr. Matitashvili. 

How do FSH levels affect fertility?

As you may have surmised, a low ovarian reserve can make it more difficult for a woman to get pregnant, but ovarian reserve should not be an indicator of a woman’s fertility. 

“In general, ovarian reserve tests should not be used as a fertility test for women who are not infertile, as they cannot predict their reproductive potential,” says Dr. Matitashvili. “In fact, FSH tests are of no value for the general population with no infertility problems.” 

However, women with low reserves may respond poorly to ovarian stimulation. Therefore, your physicians will use early follicular phase FSH levels to best counsel you regarding your response to fertility treatments, expectations from IVF stimulation, and oocyte yield from the cycle. Because FSH levels may vary significantly between cycles, your doctors will likely use additional tests to check the ovarian reserve, such as AMH levels and antral-follicular count.

Can you still get pregnant with high FSH levels?

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We’ll cut right to the chase: yes! As Dr. Tamar Matitashvili stated, these FSH tests are mainly performed to help predict ovarian response during IVF and to help your physicians better devise a plan for your treatment. 

“Patients with high FSH can be offered different types of fertility treatments like ovulation induction combined with IUI (intrauterine insemination) and IVF, depending on other contributing factors,” Dr. Matitashvili explains. “Infertility is a complex problem, and we cannot make any decisions concerning treatment based on just one value of the FSH test. We must look at the results of a number of tests and counsel patients accordingly.”

That being said, however, for women who have diminished ovarian reserve and high FSH levels, IVF success rates and pregnancy per cycle can be low. Therefore, after proper counseling with their team of physicians, some women may instead choose to try using a donor egg to achieve pregnancy. 

As always, your team of doctors has your best interests at heart. If you have high FSH, they will consider your specific levels in conjunction with your age and other contributing factors to determine the best course of action for you!

Brighid Flynn is a freelance writer based in Philadelphia where she lives with her husband and puppy. She is just beginning her journey toward motherhood.