Progesterone
Progesterone is a hormone central to the menstrual cycle and pregnancy, produced mainly by the ovaries after ovulation and by the placenta during pregnancy. Smaller amounts come from the adrenal glands in all sexes.
Ovulation confirmation: mid-luteal value >3 ng/mL suggests ovulation; >10 ng/mL indicates adequate luteal function. First trimester pregnancy 11-44 ng/mL.
Progesterone prepares the uterine lining for a possible pregnancy and helps sustain early pregnancy, and its rise after ovulation can confirm that ovulation occurred. Because it changes sharply across the menstrual cycle, its level is meaningful mainly in relation to cycle timing.
Higher progesterone is expected in the second half of the menstrual cycle and during pregnancy, and can occasionally reflect ovarian cysts or certain adrenal conditions. Whether a value is high depends heavily on when in your cycle it was drawn.
Low progesterone may indicate that ovulation did not occur or reflect the follicular phase or menopause, with meaning that differs by sex, cycle phase, and pregnancy status.
There is no single target, because progesterone is highly specific to sex, menstrual cycle phase, and pregnancy, often measured about a week before an expected period to assess ovulation. A clinician can interpret your value against your cycle timing.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.