What is the normal range for progesterone?

Progesterone—commonly referred to as the “pregnancy hormone” or “luteal hormone”—is a steroid hormone secreted primarily by the ovaries. It plays a critical role in maintaining the endometrium (uterine lining) and supporting early pregnancy. During early gestation, progesterone promotes fetal growth and development. Routine prenatal testing includes measuring serum progesterone levels, which may reveal abnormally low or high values. To assess whether your progesterone level falls within the normal range, it is essential to understand the reference values for different physiological stages. So, what are the normal progesterone levels? Let’s explore this below.

What Are the Normal Progesterone Levels?

Normal Progesterone Levels by Physiological Stage:
Sample Type & Timing | Conventional Unit (ng/mL) | Conversion Factor (ng/mL → nmol/L) | SI Unit (nmol/L) | Conversion Factor (nmol/L → ng/mL)

Follicular phase (serum): 0.2–0.6 ng/mL × 3.18 = 0.6–1.9 nmol/L × 0.3145.

Luteal phase (serum): 6.5–32.2 ng/mL × 3.18 = 20.7–102.4 nmol/L × 0.3145.

Week 7 of pregnancy (serum): 24.5 ± 7.6 ng/mL × 3.12 = 76.4 ± 23.7 nmol/L × 0.32.

Week 8 of pregnancy (serum): 28.6 ± 7.9 ng/mL × 3.12 = 89.2 ± 24.6 nmol/L × 0.32.

(Note: The value listed here for the follicular phase appears inconsistent with standard references; likely an error in the original text.)

Weeks 9–12 of pregnancy (serum): 38.0 ± 13.0 ng/mL × 3.12 = 118.6 ± 40.6 nmol/L × 0.32.

Weeks 13–16 of pregnancy (serum): 45.5 ± 14.0 ng/mL × 3.12 = 142.0 ± 43.7 nmol/L × 0.32.

Weeks 17–20 of pregnancy (serum): 63.3 ± 14.0 ng/mL × 3.12 = 197.5 ± 43.7 nmol/L × 0.32.

Weeks 21–24 of pregnancy (serum): 110.9 ± 35.7 ng/mL × 3.12 = 346.0 ± 111.4 nmol/L × 0.32.

Weeks 25–34 of pregnancy (serum): 165.3 ± 35.7 ng/mL × 3.12 = 514.8 ± 111.4 nmol/L × 0.32.

Week 35 of pregnancy (serum): 202.0 ± 47.0 ng/mL × 3.12 = 630.2 ± 146.6 nmol/L × 0.32.

Postmenopausal (serum): <1.0 ng/mL × 3.18 = <3.2 nmol/L × 0.3145.

Weeks 13–36 of pregnancy (serum): 55 ng/mL × 3.12 = 171.6 nmol/L × 0.32.

Term pregnancy (serum): 26 ng/mL × 3.12 = 81.1 nmol/L × 0.32.

The above table summarizes normal progesterone reference ranges across various physiological and gestational stages. Note: Reference ranges may vary slightly among laboratories due to differences in assay methodology and calibration standards. If your lab report lists values in ng/mL, multiply by the conversion factor (e.g., 3.18 for follicular-phase values) to obtain nmol/L; conversely, multiply nmol/L values by the reciprocal factor (e.g., 0.3145) to convert back to ng/mL.