Définition
Progesterone is a sex hormone produced primarily in the corpus luteum after ovulation. It prepares the uterus for pregnancy, counterbalances estrogen, promotes sleep through GABA enhancement, and has anti-inflammatory and calming neurological effects. Its decline precedes estrogen withdrawal and drives early perimenopausal symptoms.
Progesterone is produced primarily by the corpus luteum in the second half of the menstrual cycle (luteal phase) after ovulation. If pregnancy does not occur, the corpus luteum regresses, progesterone drops sharply, and menstruation follows. During pregnancy, the placenta becomes the primary progesterone source, maintaining levels that support fetal development.
Progesterone's role extends far beyond reproductive function. It is a neurosteroid with direct effects on GABA-A receptors in the brain — enhancing the inhibitory neurotransmitter system that promotes calm, reduces anxiety, and supports sleep. The allopregnanolone metabolite of progesterone is one of the most potent positive GABA-A modulators known, which is why progesterone deficiency (which precedes estrogen decline in perimenopause) produces anxiety, sleep disruption, and irritability before hot flashes even begin.
Progesterone counterbalances estrogen in uterine tissue — opposing the proliferative effects of estrogen on the endometrium. Low progesterone relative to estrogen ("estrogen dominance") is associated with heavier periods, breast tenderness, and mood instability in the late reproductive years.
Progesterone raises core body temperature by 0.3–0.5°C during the luteal phase (the basis for basal body temperature tracking). It shifts substrate metabolism toward fat oxidation, increases resting metabolic rate by approximately 150–300 calories, and elevates resting heart rate by 2–5 BPM — all relevant for women tracking performance and recovery across the cycle.
Ava Longevity · Built on the Ava Method · MMXXV