Mid-Luteal Progesterone Timing
Mid-luteal progesterone should be drawn 7 to 9 days after ovulation, which corresponds to approximately 5 to 10 days before the expected next menstrual period. 1
Optimal Timing Based on Ovulation Detection
- The most accurate timing is 7–9 days after the thermogenic shift on basal body temperature monitoring or after a documented urinary luteinizing hormone (LH) surge. 1
- This corresponds to the mid-luteal (ML) phase when progesterone secretion is most stable and representative of corpus luteum function. 2
- In women with shortened menstrual cycles (such as your 39-year-old post-tubal reversal patient), careful tracking of ovulation is essential because the luteal phase timing shifts earlier in the calendar cycle. 1
Practical Application for Shortened Cycles
- For a woman with a 24-day cycle: Draw progesterone on approximately cycle day 17–19 (assuming ovulation occurs around day 10–12).
- For a woman with a 26-day cycle: Draw progesterone on approximately cycle day 19–21 (assuming ovulation occurs around day 12–14).
- The key is counting backward 5–10 days from the expected next period, or forward 7–9 days from confirmed ovulation. 1
Interpretation Thresholds
- A mid-luteal serum progesterone level ≥10 ng/mL is considered adequate and suggestive of ovulation with sufficient corpus luteum function. 1, 3
- Levels <10 ng/mL are suggestive of luteal phase deficiency and warrant further evaluation. 1
- For cycles resulting in live birth, 86–88% had progesterone values >10 ng/mL in the mid-luteal phase. 3
Special Consideration for Post-Tubal Reversal Patients
- Women with prior tubal ligation or electrocoagulation have significantly lower mean mid-luteal progesterone levels (9.4 ± 4.7 ng/mL) compared to controls (17.4 ± 7.1 ng/mL). 4
- In this population, 62% had progesterone levels <10 ng/mL versus only 17% in controls, suggesting a higher prevalence of luteal insufficiency. 4
- This makes accurate timing and interpretation even more critical in your patient population. 4
Sampling Strategy for Borderline Results
- If a single progesterone level is ≥10 ng/mL, this is sufficient to confirm adequate luteal function. 2
- For results <10 ng/mL, consider obtaining three morning samples at hourly intervals during the mid-luteal phase to account for the pulsatile nature of progesterone secretion (7–14 pulses per 24 hours during ML phase). 2
- The pulsatile amplitude of progesterone during the mid-luteal phase ranges from 4 to 40 ng/mL, which can affect single measurements. 2
Common Pitfalls to Avoid
- Do not draw progesterone at a fixed cycle day without confirming ovulation timing—this is the most common error and leads to misinterpretation in women with variable cycle lengths. 1
- Avoid drawing too early (before day 5 post-ovulation), as the corpus luteum is still developing and progesterone levels may not yet reflect peak function. 2
- Avoid drawing too late (beyond day 12 post-ovulation), as progesterone levels begin declining in the late luteal phase. 2