What are normal progesterone levels at 8-12 weeks of pregnancy?

Normal Progesterone Levels at 8-12 Weeks of Pregnancy

Healthy progesterone levels at 8-12 weeks of pregnancy range from approximately 12-25 ng/mL (38-79 nmol/L), with mean values around 22 ng/mL for viable pregnancies. 1, 2

Gestational Age-Specific Values

• Week 8: Progesterone levels typically range from 12-20 ng/mL, representing the recovery phase after the luteal-placental shift 1
• Weeks 9-12: Levels stabilize and increase to approximately 15-25 ng/mL as placental progesterone production becomes fully established 1
• Mean value for viable pregnancies: Studies demonstrate a mean serum progesterone of 22.1 ng/mL during the first 8 weeks, significantly higher than nonviable gestations (10.1 ng/mL) 2

Critical Physiological Context

The 8-12 week period is particularly important because it follows the luteal-placental shift, which occurs between weeks 6-8 of gestation 1:

• Weeks 6-8: A transient decline in progesterone occurs as production transitions from the corpus luteum to the placenta, with the lowest levels typically seen at week 7 1
• After week 8: Progesterone levels show an increasing trend as the placenta assumes full responsibility for progesterone production 1

Prognostic Thresholds

Levels below 12 ng/mL at 8-12 weeks should raise concern for pregnancy viability 2, 3:

• Progesterone ≤6 ng/mL carries an 81% probability of abnormal pregnancy outcome 2
• Levels between 6-12 ng/mL represent an intermediate risk zone requiring close monitoring 3
• Progesterone ≥12 ng/mL is associated with favorable pregnancy outcomes when hCG is <2000 mIU/mL 3

Factors Affecting Progesterone Levels

Several maternal characteristics influence progesterone concentrations at 8-12 weeks 1:

• Maternal age: Older maternal age is associated with variations in progesterone levels 1
• Body mass index (BMI): Higher BMI affects progesterone measurements 1
• Parity: Multiparous women may have different progesterone trajectories compared to nulliparous women 1
• Gestational age: Week-by-week variation is significant, making precise dating essential 1

Important Clinical Caveats

Single progesterone measurements are most useful for predicting pregnancy outcome when hCG levels are <2000 mIU/mL 3:

• When hCG exceeds 2000 mIU/mL, ultrasound becomes the preferred diagnostic tool rather than progesterone measurement 3
• Serial progesterone measurements may be more informative than single values in borderline cases 4

Progesterone supplementation is NOT recommended for threatened miscarriage or low progesterone levels in early pregnancy 5:

• The Society for Maternal-Fetal Medicine states there is "no evidence of effectiveness" for progesterone in symptomatic threatened miscarriage 5
• Progesterone therapy is specifically indicated only for preterm birth prevention in later pregnancy, not for first-trimester complications 5