Progesterone Dynamics Across the Menstrual Cycle

Timing of Low Progesterone

• In a typical 28‑day cycle, progesterone remains at low baseline levels from the onset of menstruation until ovulation, which generally occurs between days 9 and 20. 1

Hormonal Changes Around Ovulation

• Ovulation marks the transition from the follicular to the luteal phase and is preceded by a rapid surge in luteinizing hormone, estrogen, and follicle‑stimulating hormone. 2, 3
• Following ovulation, serum progesterone rises progressively throughout the luteal phase, reaching its highest concentration in the mid‑luteal period. 2, 3

Luteal‑Phase Peak and Clinical Relevance

• The luteal phase exhibits the highest progesterone concentrations, a pattern that is clinically important because elevated progesterone can precipitate cyclic attacks in acute hepatic porphyria. 4, 5, 6

Mid‑Luteal Progesterone Testing

• Measuring progesterone on cycle days 25‑26 (mid‑luteal) is used to confirm ovulation; values below roughly 6 nmol/L are indicative of anovulation. 7