For the best chance of getting pregnant, a day 3 FSH level below 10 mIU/mL is generally considered favorable. Women under 33 ideally have levels below 7.0 mIU/mL, while those in their late 30s can expect slightly higher baselines, up to about 8.5 mIU/mL, and still fall within a normal range. Once FSH climbs above 10, fertility clinics begin to see lower pregnancy rates, and levels above 15 mIU/mL signal a much steeper decline in the odds of conceiving.
What FSH Actually Tells You
FSH, or follicle-stimulating hormone, is produced by the pituitary gland in your brain. Its job is to stimulate your ovaries to mature an egg each cycle. When your ovaries are responding well, they send signals back to the brain that keep FSH at moderate levels. When fewer eggs remain or the ovaries aren’t responding as strongly, the brain compensates by pumping out more FSH, essentially working harder to get the same result. That’s why a higher FSH number points to a shrinking egg supply rather than better fertility.
FSH is a measure of egg quantity, not egg quality. Two women with identical FSH readings can have very different outcomes depending on age, overall health, and factors that blood tests don’t capture. Still, it remains one of the most commonly ordered fertility tests because it’s inexpensive, widely available, and offers a useful first look at ovarian reserve.
Normal FSH Ranges by Cycle Phase
FSH fluctuates throughout your menstrual cycle, which is why a single number without context can be misleading. During the follicular phase (the first half of your cycle, before ovulation), normal levels run between 1.4 and 9.9 mIU/mL. At the ovulatory peak, FSH surges to 6.2 to 17.2 mIU/mL, then drops back down to 1.1 to 9.2 mIU/mL during the luteal phase (after ovulation).
For fertility purposes, the number that matters most is your “basal” FSH, drawn on day 2, 3, or 4 of your cycle. This early reading captures your baseline before hormonal shifts kick in, giving the clearest picture of how hard your body is working to recruit a follicle.
Day 3 FSH Targets by Age
Your expected baseline shifts slightly as you age. Data from fertility clinics shows the following day 3 thresholds for normal ovarian function:
- Under 33: below 7.0 mIU/mL
- 33 to 37: below 7.9 mIU/mL
- 38 to 40: below 8.4 mIU/mL
- 41 and older: below 8.5 mIU/mL
These are averages for women with normal ovarian reserve at each age. Levels above these cutoffs don’t automatically mean you can’t conceive, but they may indicate premature ovarian aging, meaning your egg supply is declining faster than expected for your age. Research defines premature ovarian aging using those same thresholds: 7.84 mIU/mL or higher for women under 33, 8.12 for those 33 to 37, and 8.47 for women 38 to 41.
When FSH Levels Affect Pregnancy Chances
The practical cutoffs fertility specialists watch for are 10, 15, and 20 mIU/mL. Below 10, ovarian reserve is considered favorable. Between 10 and 12, most clinics classify it as diminished ovarian reserve, meaning fewer eggs are available, though pregnancy is still possible. Above 15, the drop in IVF success rates becomes pronounced. Above 20, pregnancy through IVF becomes extremely rare.
At 40 mIU/mL or above, the reading suggests premature ovarian insufficiency if you haven’t yet reached the typical age of menopause. At that level, the egg supply is largely depleted.
These numbers apply most directly to IVF outcomes, but they track with natural conception as well. A higher FSH means fewer eggs are maturing each cycle, which narrows the window of opportunity month to month. It doesn’t mean the eggs you do have are necessarily poor quality, just that there are fewer of them to work with.
Why AMH May Be More Informative
FSH has an important limitation: it’s specific but not sensitive. That means a high FSH reliably points to diminished ovarian reserve, but a normal FSH doesn’t guarantee your reserve is fine. FSH can stay in the normal range even as your egg supply is quietly declining.
Anti-Müllerian hormone (AMH) has largely replaced FSH as the preferred ovarian reserve marker at many clinics. AMH tends to drop before FSH rises, making it better at catching subtle declines earlier. AMH also stays relatively stable throughout your cycle, so you don’t need to time the blood draw to a specific day. According to the American Society for Reproductive Medicine, AMH is a more sensitive measure of ovarian reserve than FSH.
That said, neither test predicts egg quality or guarantees pregnancy. Both AMH and FSH measure quantity. Meta-analyses show that AMH as a standalone number is only weakly predictive of actual pregnancy and live birth rates. The real value of these tests is in helping you and your provider choose the right treatment approach and set realistic expectations, not in delivering a pass/fail verdict on your fertility.
Signs Your FSH Might Be Elevated
Elevated FSH doesn’t always come with obvious symptoms, which is why testing matters. But there are cycle changes that can hint at declining ovarian reserve before you get blood work done. Shorter menstrual cycles are one of the earliest signs. If your period starts arriving a few days earlier than it used to, that can reflect a shorter follicular phase driven by higher FSH pushing your ovaries to recruit follicles faster. Lighter periods, skipped cycles, or increased irregularity can also point in this direction, though these changes have many possible causes.
FSH and Male Fertility
FSH isn’t just relevant for women. In men, it drives sperm production, and elevated levels can signal that the testes aren’t functioning normally. The standard lab reference range for men is 1.4 to 18.1 IU/L, but research suggests that range may be too generous. One study found that men with FSH above 4.5 IU/L were more likely to have abnormal sperm concentration and morphology. At levels above 7.5, the risk of abnormal semen quality was five to thirteen times higher than in men with FSH below 2.8.
If a couple is struggling to conceive, FSH testing for both partners can help identify whether the issue is on the female side, the male side, or both.
Can You Lower Elevated FSH?
This is where expectations need to be realistic. No intervention has been reliably shown to increase ovarian activity or restore a depleted egg supply. The American Society for Reproductive Medicine’s 2024 guidelines on premature ovarian insufficiency state this clearly: there are no proven treatments to boost natural conception rates once the follicle pool is significantly diminished. Supplements, herbal remedies, and acupuncture lack sufficient evidence of benefit for this purpose.
What does help is overall health. Maintaining a healthy weight, staying physically active, eating well, and avoiding smoking all support reproductive function and reduce cardiovascular and bone health risks that come with hormonal changes. These habits won’t reverse ovarian aging, but they create the best possible environment for the eggs you do have. If your FSH is elevated and you’re trying to conceive, the most productive conversation is usually with a reproductive endocrinologist about whether IVF, donor eggs, or other assisted options make sense given your specific numbers and goals.