What is Serum Progesterone?
💡 Serum progesterone confirms ovulation when measured mid-luteal (Day 21 in 28-day cycle). Ovulatory: >30 nmol/L (>10 ng/mL). In IVF: late-follicular progesterone rise >1.5 ng/mL before trigger = premature luteinisation (poorer outcome). Luteal support in IVF: progesterone pessaries/injections maintain levels ≥10–30 ng/mL post-transfer.
Serum progesterone is a blood test measuring the level of progesterone — the hormone produced by the corpus luteum after ovulation. It is used to confirm ovulation (mid-luteal progesterone), monitor IVF luteal support, and detect premature luteinisation during IVF stimulation. It is one of the most clinically informative female hormone tests in fertility practice.
🇮🇳 India Context: Serum Progesterone is widely assessed and treated across major Indian fertility centres including Chennai, Mumbai, Bangalore, Delhi, and Hyderabad.
What are the key characteristics of Serum Progesterone?
- Mid-luteal (Day 21) progesterone: ovulatory if >30 nmol/L (>10 ng/mL); levels 3–10 nmol/L = suboptimal/anovulatory; <3 nmol/L = almost certainly anovulatory
- Timing: in a 28-day cycle, measure on Day 21 (7 days before expected next period); in irregular cycles, adjust to Day of LH surge + 7 days; better to do post-positive OPK+7
- IVF late-follicular progesterone: measured on trigger day; >1.5 ng/mL (>4.8 nmol/L) = premature luteinisation → reduced fresh transfer success rate → consider freeze-all strategy
- IVF luteal support: after egg retrieval, corpus luteum is absent (granulosa cells removed); exogenous progesterone (pessaries 400–800mg/day, Crinone gel, or IM progesterone 50mg/day) maintains luteal phase
- Post-transfer progesterone monitoring: target levels vary by formulation; most centres aim for serum progesterone ≥10–20 ng/mL at Day 4–7 post-transfer on vaginal supplementation
- Low post-transfer progesterone: associated with higher miscarriage risk; dose increase or switch to IM progesterone; some studies show benefit of rescue supplementation
- Corpus luteum rescue: if hCG positive at 10–14 days post-transfer, corpus luteum support continues until 8–10 weeks gestation (placenta takes over progesterone production)
- Anovulation detection: consistently low mid-luteal progesterone (<15 nmol/L) across 2+ cycles = probable anovulation; investigate with Day 3 FSH, AMH, LH, prolactin, thyroid
How does Serum Progesterone work?
Why does Serum Progesterone matter in fertility?
Serum progesterone is the most clinically useful confirmatory test for ovulation — it is the only test that directly confirms the hormonal consequence of ovulation (corpus luteum formation and progesterone secretion). A negative OPK or absence of EWCM is not proof of anovulation; a Day 21 progesterone <15 nmol/L strongly suggests it. In IVF, late-follicular progesterone rise (premature luteinisation) is a growing concern — affecting 5–38% of stimulated cycles depending on protocol. Studies show significantly lower live birth rates per fresh transfer when trigger-day progesterone exceeds 1.5 ng/mL, making freeze-all the clinically appropriate response. Post-transfer progesterone monitoring and dose adjustment is now standard practice at high-quality IVF centres, replacing the historical "one dose fits all" pessary approach.
What are related terms to Serum Progesterone?
Progesterone
Progesterone is a hormone produced by the corpus luteum — the structure left in …
Luteal Phase
The luteal phase is the second half of the menstrual cycle, beginning at ovulati…
Ovulation
Ovulation is the release of a mature oocyte (egg) from a dominant ovarian follic…
Embryo Transfer
Embryo Transfer is the final step of the IVF process. A laboratory-cultured embr…
IVF (In Vitro Fertilisation)
IVF (In Vitro Fertilisation) is an assisted reproductive technology (ART) in whi…
FAQs about Serum Progesterone
What is a serum progesterone test?
Serum progesterone is a blood test measuring progesterone levels. In fertility practice it is used for: (1) confirming ovulation — measured mid-luteal (Day 21 in a 28-day cycle); ovulatory if >30 nmol/L (>10 ng/mL); (2) detecting premature luteinisation in IVF — if trigger-day progesterone >1.5 ng/mL, fresh transfer outcome is reduced; (3) monitoring luteal support in IVF post-transfer — ensures supplemented levels are adequate.
What is a normal progesterone level after ovulation?
Mid-luteal progesterone (Day 21 of a 28-day cycle): >30 nmol/L (>10 ng/mL) = ovulatory. 15–30 nmol/L = borderline — probably ovulating but luteal support may be suboptimal. <15 nmol/L = likely anovulatory or test mistimed. <3 nmol/L = almost certainly anovulatory. In irregular cycles, measure 7 days after a positive OPK rather than on a fixed day — this ensures the test is mid-luteal regardless of cycle length.
What is premature luteinisation in IVF?
Premature luteinisation is a rise in serum progesterone (>1.5 ng/mL) in the late follicular phase during IVF stimulation, before the trigger shot is given. It occurs in 5–38% of stimulated cycles and indicates early corpus luteum-like activity — the endometrium may advance out of sync with the embryo. Studies show significantly lower fresh transfer live birth rates when trigger-day progesterone exceeds 1.5 ng/mL. Response: freeze all embryos and transfer in a subsequent FET cycle.
How much progesterone is needed after IVF embryo transfer?
Most IVF centres aim for serum progesterone ≥10–20 ng/mL (30–65 nmol/L) at Day 4–7 post-transfer on vaginal suppository supplementation (400–800mg/day). Vaginal progesterone (pessaries/Crinone) produces adequate local endometrial levels but relatively low serum levels — so serum measurement may underestimate tissue levels. If serum progesterone is low (<10 ng/mL), dose increase or switch to IM progesterone (50mg/day) is indicated.
What does low progesterone after IVF transfer mean?
Low serum progesterone (<10 ng/mL) post-embryo transfer, especially on Day 4–7, is associated with higher miscarriage risk and lower implantation rates in studies. Management: increase vaginal progesterone dose, add vaginal pessaries to existing regimen, or switch to IM progesterone. The "rescue" approach (increasing progesterone when levels are found low before the beta-hCG test) has shown benefit in several RCTs. Monitoring progesterone post-transfer is now standard at quality IVF centres.
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