When in your cycle should you test?
Pick a hormone to see when it is usually tested. Your lab order or clinician may give different timing, and theirs comes first.
Progesterone
About 1 week before your next period is expected, not on a fixed day such as day 21.
The American Society for Reproductive Medicine (ASRM) says a progesterone measurement to check for ovulation should generally be taken approximately 1 week before the expected start of the next period, rather than on any one specific cycle day. A level above 3 ng/mL is presumptive evidence of recent ovulation. A single value can confirm ovulation but not judge the quality of the luteal phase. Your lab order sets the day for your own test.
Source: Fertility evaluation of infertile women: a committee opinion (ASRM, 2021) · Read more
Estradiol
It depends on the question. For an ovarian reserve workup, early in the cycle.
ASRM describes early-follicular (basal) FSH and estradiol testing for ovarian reserve, and gives day 2, 3 or 4 of the cycle for FSH. It says basal estradiol alone should not be used to screen for diminished ovarian reserve; it helps in reading a normal FSH. This source is about fertility testing. It gives no cycle day for estradiol tested for other reasons, so follow your lab order or your clinician.
Source: Testing and interpreting measures of ovarian reserve: a committee opinion (ASRM, 2020) · Read more
FSH
For ovarian reserve, usually early in the cycle, on day 2, 3 or 4. For other questions, follow your lab order.
ASRM says FSH levels vary a lot between and within cycles, which limits how far a single measurement can be trusted. It also says AMH has largely replaced basal FSH and estradiol as a marker of ovarian reserve. MedlinePlus says women who have periods may need to be tested at a specific time in the cycle because FSH changes through the month.
Source: Testing and interpreting measures of ovarian reserve: a committee opinion (ASRM, 2020) · Read more
LH
Your lab order or clinician decides. The source says you may need a specific time in your cycle but does not give a day.
MedlinePlus says that if you have periods, you may need to have the LH test at a specific time in your menstrual cycle. It also says you may need to stop certain medicines or supplements first, and that you should not stop a prescription medicine unless your provider tells you to.
Source: Luteinizing Hormone (LH) Levels Test (MedlinePlus) · Read more
AMH
Any day. Timing in the cycle does not matter.
ASRM groups AMH as a cycle-day-independent test and says AMH stays relatively consistent within and between menstrual cycles. It also says AMH may be lower in women who are using hormonal contraceptives, so results need careful reading in that case.
Source: Testing and interpreting measures of ovarian reserve: a committee opinion (ASRM, 2020) · Read more
Testosterone
Morning, 8 to 10 a.m., and early in the cycle where possible.
This UK guideline is about investigating androgen excess in women. It says samples should be collected in the morning, at 8 to 10 a.m., after an overnight fast, and where possible in the early follicular phase. It adds that early in the cycle may not be possible when the cycle is disrupted or absent. It also says testosterone does not appear to fluctuate significantly across the cycle when measured by LC-MS/MS, a mass spectrometry method. Your lab order may differ.
Source: Society for Endocrinology Clinical Practice Guideline for the Evaluation of Androgen Excess in Women (2025) · Read more
Prolactin
Usually 3 to 4 hours after you wake up. The source gives no cycle day.
MedlinePlus says prolactin levels change through the day, so the blood sample is usually scheduled for three to four hours after you wake up. You may be asked to fast for several hours. Small rises can come from stress, exercise and sex, and some medicines and vitamins can affect levels, so tell your provider what you take.
Source: Prolactin Levels Test (MedlinePlus) · Read more