It is hard to answer this question exactly without knowing what your situation is. For example, are you just being worked up by your doctor
for trouble conceiving? Or are you in the middle of fertility treatments? Depending on your situation, the exact timing of when the follicle stimulating hormone test is done is more critical. I would recommend following up with the doctor who ordered this test.
As you know, follicle stimulating hormone is important in the body because it helps the eggs mature inside the ovaries. Doctors
often measure follicle stimulating hormone levels as a way to gauge fertility. The standard way is to do this test early in the cycle, typically around day three of the cycle. This is because the hormone levels fluctuate throughout the cycle, so having a standardized time in the cycle for checking levels helps with interpretation. This does not however mean that a level checked late in the cycle is always entirely meaningless, especially if you are just starting workup for trouble conceiving.
Again, I would recommend following up with your doctor who ordered this test as soon as the results come back. They will be able to explain what they were looking for with the test and what they think the results are likely to mean.