Progesterone

What is Progesterone?

Progesterone is a steroid hormone produced primarily by the ovaries after ovulation. It prepares the uterus for pregnancy and maintains early pregnancy.

Why is it Important?

Progesterone is essential for:

• Preparing the uterine lining for implantation
• Maintaining early pregnancy (first 10 weeks)
• Regulating menstrual cycle
• Preventing premature uterine contractions
• Supporting fetal development

Normal Ranges by Phase and Condition

Group/Phase	Range	Unit
Follicular Phase (pre-ovulation)	0.1 – 0.9	ng/mL
Luteal Phase (post-ovulation)	2.0 – 25	ng/mL
Mid-Luteal Peak	5.0 – 20	ng/mL
Postmenopausal	0.1 – 0.5	ng/mL
First Trimester Pregnancy	10 – 44	ng/mL
Second Trimester Pregnancy	19 – 82	ng/mL
Third Trimester Pregnancy	65 – 290	ng/mL
Men	0.1 – 0.3	ng/mL

What Do Abnormal Results Mean?

High Progesterone

Common causes include:

• Normal pregnancy
• Molar pregnancy or ovarian cysts
• Adrenal hyperplasia
• Certain ovarian tumors
• Progesterone supplementation

Low Progesterone

In women of reproductive age, common causes include:

• Anovulation (lack of ovulation)
• Luteal phase defect
• Threatened miscarriage
• Ectopic pregnancy
• Polycystic ovary syndrome (PCOS)
• Perimenopause

Mid-Luteal Progesterone for Ovulation Confirmation

A progesterone level > 3 ng/mL measured 7 days after suspected ovulation confirms ovulation occurred.

When Should You Get Tested?

Progesterone testing may be ordered if you have:

• Infertility or difficulty conceiving
• Irregular menstrual periods
• Suspected miscarriage or ectopic pregnancy
• Abnormal uterine bleeding
• Monitoring ovulation induction therapy
• Confirming ovulation in fertility treatments

Timing matters: For ovulation confirmation, test on day 21 of a 28-day cycle (or 7 days after suspected ovulation).