The purpose of progesterone is to prepare the uterus for pregnancy, as well as maintaining pregnancy. Twelve weeks after gestation, the umbilical cord produces progesterone.
Progesterone is normally produced by the corpus luteum, peaking during the midluteal phase of the menstrual cycle. Progesterone levels are the best way to evaluate if ovulation occurred, health of the corpus luteum and chances of spontaneous abortion.
4-5 days after ovulation, progesterone levels rise and continue to do so in pregnancy for 9-32 weeks after gestation by as much as 100 times that of a non-pregnant female. Progesterone levels in females carrying twins are usually higher then single pregnancies. Progesterone levels used with β-HCG levels assists in assessing uterine pregnancies from ectopic pregnancies.
Progesterone levels are increased in:
- Congenital adrenal hyperplasia
- Lipid ovarian tumor
- Chorionnepithelioma of the ovary
- Molar pregnancy
Progesterone levels are decreased in:
- Threatened spontaneous abortion
- Galactorrhea-amenorrhea syndrome (hypogonadism)
Progesterone Levels in the Mid-Luteal Phase
The mid-luteal phase occurs approximately 7 days after ovulation (around day 21 in a standard 28-day cycle). This is when progesterone levels peak, as the corpus luteum is actively producing progesterone to support a potential pregnancy.
Normal Progesterone Levels in the Mid-Luteal Phase
- 5 to 20 ng/mL
- Levels above 10 ng/mL generally indicate ovulation has occurred.
- Levels may vary depending on factors like cycle length and individual hormonal balance.
