AMH is the most important single test for ovarian reserve and can be drawn any day of the cycle. FSH and estradiol are tested on cycle day 2–4 and assess how hard your ovaries are working. Progesterone is tested 7 days after suspected ovulation to confirm it actually happened. LH is most useful via urine OPKs to detect the ovulation surge. TSH screens for thyroid issues that can silently impair fertility.
The Hormones and What They Do
AMH (Anti-Müllerian Hormone)
What it measures: The number of small antral follicles in your ovaries — essentially, your remaining egg supply (ovarian reserve). AMH is produced by the granulosa cells of growing follicles, so higher AMH means more follicles, which means more eggs available.
When to test: Any day of your cycle. AMH doesn't fluctuate significantly across the menstrual cycle, making it the most convenient fertility hormone to test.
| AMH (ng/mL) | Age Under 35 | Age 35–39 | Age 40+ |
|---|---|---|---|
| Over 3.5 | High — may indicate PCOS | Excellent reserve | Very reassuring |
| 1.5–3.5 | Normal | Good reserve | Above average for age |
| 1.0–1.5 | Normal-low | Slightly diminished | Expected range |
| 0.5–1.0 | Diminished | Diminished | Low but IVF may still work |
| Under 0.5 | Significantly diminished | Very low | Limited response to stimulation expected |
AMH measures quantity, not quality
A 28-year-old with low AMH still has age-appropriate egg quality. A 42-year-old with high AMH still faces age-related quality decline. AMH tells you how many eggs you can retrieve in an IVF cycle and approximately how much time you have before menopause — it does not predict natural conception rates or egg health.
FSH (Follicle-Stimulating Hormone)
What it measures: How hard your brain is working to stimulate your ovaries. FSH is produced by the pituitary gland and tells the ovaries to develop follicles. When ovarian reserve is low, the brain compensates by producing more FSH — like pressing the accelerator harder.
When to test: Cycle day 2–4 only. FSH fluctuates throughout the cycle, and only the early-cycle baseline is clinically meaningful.
Normal range: Under 10 IU/L is reassuring. 10–15 is borderline. Over 15 suggests diminished ovarian reserve. Over 25 is significantly elevated.
Key caveat: FSH can vary cycle to cycle. A single elevated reading warrants a retest. However, even one elevated FSH is considered clinically significant — your best FSH reading does not override your worst one.
Estradiol (E2)
What it measures: The primary estrogen produced by growing ovarian follicles. On cycle day 2–4, it should be low (under 80 pg/mL). If it's elevated early in the cycle, it may be masking a high FSH — the follicle has started growing early, producing estrogen that suppresses FSH via negative feedback. This is why FSH and estradiol are always tested together.
When to test: Cycle day 2–4, drawn alongside FSH.
LH (Luteinizing Hormone)
What it measures: The hormone that triggers ovulation. A surge of LH causes the mature follicle to rupture and release the egg. Baseline LH (day 2–4) is useful for diagnosing PCOS (often elevated relative to FSH, with LH:FSH ratio greater than 2:1).
Most useful as: Urine OPK tests that detect the LH surge 24–36 hours before ovulation. Blood LH is less useful for ovulation timing because it requires precisely timed draws.
Progesterone
What it measures: Whether ovulation occurred. Progesterone is produced by the corpus luteum (the collapsed follicle) after ovulation. A level above 3–5 ng/mL confirms ovulation. Many doctors prefer to see 10+ ng/mL for reassurance of adequate luteal function.
When to test: 7 days after suspected ovulation (roughly cycle day 21 in a 28-day cycle, but adjust based on your actual ovulation day). Testing too early or too late will give a misleadingly low result.
Getting the timing right for progesterone
If you ovulate on day 16, your progesterone draw should be on day 23 (16 + 7), not the standard “day 21.” Use your OPK positive date + 8 days as the target blood draw day. A low progesterone result from a poorly-timed draw is one of the most common sources of unnecessary anxiety in fertility testing.
TSH (Thyroid-Stimulating Hormone)
What it measures: Thyroid function. Both hypothyroidism (underactive) and hyperthyroidism (overactive) can impair ovulation, increase miscarriage risk, and affect fetal brain development.
Optimal range for TTC: Under 2.5 mIU/L. The general population “normal” range goes up to 4.5, but reproductive endocrinologists prefer a tighter target for women trying to conceive. If your TSH is 3.0–4.5, you may have subclinical hypothyroidism that's subtly impairing fertility.
Prolactin
What it measures: A pituitary hormone that, when elevated (hyperprolactinemia), can suppress GnRH and disrupt ovulation. Common causes include stress, medications (especially antipsychotics and some antidepressants), pituitary adenomas, and even excessive nipple stimulation.
Normal range: Under 25 ng/mL in non-pregnant women.
The Complete Day 3 Panel
| Test | Day to Draw | What It Tells You | Cost (Without Insurance) |
|---|---|---|---|
| AMH | Any day | Ovarian reserve (egg count) | $50–$150 |
| FSH | Day 2–4 | Ovarian effort level | $30–$75 |
| Estradiol | Day 2–4 | Validates FSH accuracy | $30–$75 |
| LH | Day 2–4 | Baseline; PCOS screening | $30–$75 |
| TSH | Any day | Thyroid function | $25–$50 |
| Prolactin | Any day (morning, fasting) | Pituitary function | $30–$75 |
| Progesterone | Ovulation + 7 days | Confirms ovulation | $30–$75 |
| Vitamin D | Any day | Linked to implantation and IVF success | $30–$60 |
Costs are approximate for out-of-pocket in the US. Insurance typically covers these when ordered for infertility evaluation.
Understanding Your Results?
If your bloodwork suggests diminished reserve or hormonal imbalances, knowing your treatment options early is critical.
Explore Treatment Options