FSH and pregnancy: What you need to know

Follicle-stimulating hormone (FSH) has an important role to play in your menstrual cycle. But if you’re not quite sure what it is or why it matters, you’re certainly not the only one. It’s not as well known as some of the other big player hormones like estrogen and progesterone.

But is it something you should be keeping an eye on, especially if you’re trying to conceive? This guide will walk you through everything you need to know about FSH, with a little help from Dr. Renita White, obstetrician and gynecologist, US. We’ll explain the role of FSH in fertility and discover when doctors might recommend looking at your hormone levels using an FSH test.

Key takeaways: FSH and pregnancy

• Follicle-stimulating hormone helps your ovaries get ready to release an egg each month (ovulation). It does this by telling your ovarian follicles, which contain your eggs, to grow.
• This means FSH levels help regulate your cycle and play a role in ovulation, which is key if you’re trying to conceive.
• Doctors don’t really think in terms of “normal” FSH levels. But if you’ve been told your FSH is particularly high or low, it might be a sign that you have a hormonal health condition like polycystic ovary syndrome (PCOS) or thyroid problems. Rest assured though, having an FSH level outside the average range doesn’t automatically mean you won’t get pregnant.
• You probably don’t need to worry about your FSH level unless your doctor has recommended hormone testing. This only happens in certain circumstances, like if you have irregular cycles and you’re struggling to get pregnant. 

What is FSH?

Lots of hormones — chemicals that send messages to other parts of the body — are released at different points in the menstrual cycle. Follicle-stimulating hormone, which is made by the pituitary gland in the brain, is one of them. But, despite having “follicle” in the name, it doesn’t have anything to do with hair. Instead, it refers to the follicles in ovaries. These are small sacs filled with fluid that contain underdeveloped eggs. 

FSH tells these follicles to grow until a mature egg is ready to be released at ovulation. As the follicles grow, they release the hormone estrogen into your blood, which helps regulate your menstrual cycle.

“So FSH is responsible for stimulating the growth of follicles in your ovaries, increasing estrogen levels, and preparing the body for pregnancy,” Dr. White sums up. FSH also helps control the amount of sperm that testicles make.

What role does FSH play in fertility?

Let’s look at FSH’s role in fertility and your menstrual cycle in a little more detail. 

FSH levels change throughout your menstrual cycle.

• After your period (during your follicular phase), FSH rises to trigger ovary follicle growth.
• Mid-cycle (ovulation), FSH peaks to help release a mature egg into your fallopian tubes.
• After ovulation (luteal phase), levels drop as your body prepares for a potential pregnancy.

As FSH tells your ovary follicles to grow, this ultimately leads to the release of a mature egg about midway through your cycle. The egg travels to your fallopian tubes, where it might be fertilized by a sperm if you have unprotected sex around this time.

If you’re trying to conceive, you can use a period-tracking app like Flo to learn more about ovulation, track your symptoms, and get to know your body’s fertility signals.

What is a normal FSH range to get pregnant?

Now that we've covered the vital role FSH plays in fertility and your menstrual cycle, you might be wondering what your levels need to be to indicate everything is working as it should. 

“We shy away from using the word ‘normal’ when referring to people’s bodies as we’re all so different,” says Dr. White.

However, an average FSH level for fertility is often between 4.7 to 21.5 mIU/mL, depending on your cycle phase. Levels outside this range may cause your doctor to take a deeper look to find out why, especially if you’re struggling to conceive. But you’d only get your FSH tested if your doctor recommended an FSH blood test, which only happens in certain circumstances. Have a chat with your doctor if you want to know more about when an FSH test would be suggested, and rest assured it’s certainly not something you need to do at home.

It’s important to get the timing right when you’re testing for FSH, as it varies so much throughout your menstrual cycle. Doctors recommend testing for FSH on day three of your cycle (the third day of your period), but they’ll walk you through everything you need to know if they recommend that you have the test.

Can your FSH levels be too high to get pregnant?

It can sometimes be a little trickier to get pregnant if you have elevated FSH levels. High FSH is seen in a few conditions, such as:

• PCOS: A hormonal condition that can affect ovulation
• Diminished ovarian reserve: When your body has fewer eggs
• Perimenopause: The transition through menopause, including the years before your final period and 12 months afterward
• Premature ovarian insufficiency: When the ovaries stop working properly before the age of 40

High FSH levels don’t always mean you definitely won’t be able to conceive, but it’s always worth discussing with your doctor if you’re concerned about it. 

Can your FSH levels be too low to get pregnant?

Again, having FSH levels on the low side doesn’t necessarily mean you’ll struggle to get pregnant. But low FSH might suggest a health condition like your pituitary gland (which controls lots of your hormones) being out of whack. These conditions can sometimes affect ovulation (which can make conceiving trickier), but the good news is, they are often treatable. Your doctor will be able to advise on next steps and any fertility treatments that might be needed.

Understanding how FSH and pregnancy fit together

FSH is an important part of fertility, but it’s just one element of it. If your menstrual cycle is regular, and you’re not experiencing fertility challenges, you probably don’t need to think about FSH. But if you’ve been trying to get pregnant without success for a year (six months if you’re over 35, or right away if you’re 40 or over), talk to your doctor about testing and treatment options.

“FSH levels are not typically checked unless your menstrual cycle is irregular,” Dr. White assures. “If you are trying to conceive, and your cycle is not predictable, seek medical guidance.”