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 Luteal Phase
The luteal phase occurs after ovulation and lasts until the onset of menstruation or pregnancy. During this phase, progesterone levels peak, as the corpus luteum (formed from the ruptured follicle) secretes progesterone to prepare the uterus for potential implantation of a fertilized egg.
Normal Progesterone Levels in the Luteal Phase
- 2-25 ng/mL 6.4-79.5 nmol/L