Overview.
Unlike most blood panels that can be drawn any day, several key fertility hormones must be tested at specific points in the menstrual cycle to be interpretable. Testing FSH on Day 15 instead of Day 3, or progesterone on Day 14 instead of Day 21, produces results that look abnormal when they may not be — or miss significant findings entirely. This guide maps out exactly what to test, when, and for both partners.
Context: Inappropriate test timing is one of the most common errors in fertility evaluation. Day 3 hormones drawn on Day 10 cannot be compared to reference ranges. Day 21 progesterone tested in a woman with a 35-day cycle will catch the wrong phase entirely. The ASRM emphasises that appropriate test timing is as important as test selection.
Key takeaways.
- Day 1 = first day of full menstrual flow (not spotting)
- Day 3 hormones (FSH, LH, E2) must be drawn on cycle days 2-5
- AMH can be drawn on any cycle day — it's cycle-independent
- Day 21 progesterone: adjust to 7 days post-ovulation for non-28-day cycles
- Male partner testing has no cycle timing — can start immediately
- Both partners should be evaluated simultaneously, not sequentially
- Under 35: evaluate after 12 months. 35-39: after 6 months. 40+: immediately
Female Partner: Cycle-Timed Testing.
A standard 28-day cycle has two phases: follicular (Days 1-14) and luteal (Days 15-28), separated by ovulation. Testing windows are designed around these physiological phases.
- Days 2-5 (Day 3 ideal): FSH, LH, Estradiol
- Early follicular phase baseline. FSH reveals ovarian response; elevated >10-12 mIU/mL suggests diminished reserve. Elevated E2 (>80 pg/mL) can mask poor FSH. LH:FSH >2:1 = PCOS pattern. If you miss Day 3, wait for the next cycle.
- Any Day: AMH
- Anti-Müllerian Hormone is cycle-independent. Best marker of ovarian reserve quantity. Note: OCPs suppress AMH by ~30%, so testing after stopping provides a truer baseline.
- Day 21 (or 7 DPO): Progesterone
- Confirms ovulation. For a 35-day cycle, test on Day 28 (not Day 21). For a 21-day cycle, test on Day 14. Use ovulation predictor kits if cycles are irregular to identify the correct window.
- Any Day: TSH, Free T4, Prolactin, Vitamin D
- Not cycle-dependent. Can be drawn with Day 3 hormones for convenience. Prolactin: draw fasting, relaxed, without recent breast stimulation.
- Any Day (if PCOS suspected): Testosterone, DHEA-S, Fasting Insulin
- Assess androgen excess and metabolic component. Fasting required for insulin.
Male Partner: No Cycle Constraints.
Male testing can begin immediately — no waiting for a specific cycle day.
- Semen Analysis
- 2-7 days abstinence. Deliver to lab within 30-60 minutes at body temperature. Minimum two analyses, 2-3 months apart.
- Hormonal Panel (7-10 AM)
- Total testosterone (must be morning draw), FSH, LH, prolactin. Add estradiol if obesity or gynaecomastia present. Add SHBG if borderline testosterone.
Pre-Conception Checklist (Before Trying).
Distinct from a fertility workup (triggered by failure to conceive), this is valuable at any age before trying.
- Female: CBC, blood type, rubella/varicella immunity
- Screen for anaemia, Rh factor (for pregnancy management), and immunity to infections dangerous in pregnancy.
- Female: TSH, folate/B12, vitamin D, HbA1c
- Undetected hypothyroidism causes early miscarriage. Folate prevents neural tube defects. Vitamin D supports implantation. HbA1c screens for diabetes.
- Both partners: STI screening, carrier screening
- Chlamydia, gonorrhoea, HIV, syphilis, hepatitis B. Carrier screening for cystic fibrosis, spinal muscular atrophy, fragile X (discuss with provider).
- Male: Semen analysis baseline
- Establishes baseline early rather than waiting for a problem to appear.
Age-Based Evaluation Timeline.
The ASRM provides clear age-stratified guidance for when to seek formal fertility evaluation:
- Under 35
- Seek evaluation after 12 months of unprotected regular intercourse. Pre-conception bloodwork is still valuable at any age. Test sooner if known risk factors exist.
- 35-39
- Seek evaluation after 6 months. AMH testing is particularly important — reserve can decline significantly between ages 35-38. Initiate male evaluation concurrently.
- 40+
- Immediate evaluation recommended. Ovarian reserve assessment (AMH + Day 3 FSH/E2 + AFC) is urgent. AMH below 0.5 ng/mL warrants prompt reproductive endocrinologist referral.
- Male Partner (All Ages)
- Evaluate simultaneously with female partner — not after. Male factor accounts for ~50% of infertility. Sperm quality declines after ~45-50 but less steeply than female decline.
How Often to Retest.
Retesting frequency depends on the marker and the clinical context:
- Day 3 FSH/LH/E2
- Each new treatment cycle, or annually if monitoring reserve over time.
- AMH
- Every 6-12 months if monitoring reserve. No need to retest unless circumstances change.
- Day 21 Progesterone
- Each cycle if monitoring for ovulation.
- Semen Analysis
- Minimum 2-3 months after any intervention. Repeat annually if male factor suspected.
- TSH
- Annually, or 6-8 weeks after thyroid medication change.
FAQs.
What if I have irregular cycles and can't identify Day 3?
AMH, thyroid, and prolactin testing can proceed immediately (any day). For Day 3 hormones, draw blood on days 2-5 of your next period whenever it arrives. For progesterone, use ovulation predictor kits (OPKs) to identify ovulation, then test 7 days later.
Can I do all fertility tests in one blood draw?
Partially. Day 3 hormones, AMH, TSH, prolactin, and vitamin D can all be drawn together on cycle days 2-5. But progesterone requires a separate Day 21 draw. Male partner bloodwork can be drawn on any day.
Should I test before seeing a fertility specialist?
Yes — your GP or OB/GYN can order most of these tests. Having results in hand before a specialist appointment saves a cycle of waiting and gives the specialist actionable data on day one.
I'm on birth control — can I still test fertility markers?
AMH can be tested on OCPs but will be approximately 30% lower than your true baseline. Day 3 hormones and progesterone are not interpretable while on hormonal contraception. TSH, prolactin, and metabolic markers can be tested normally.