Normal Progesterone Estrogen cycle.

 

Cycle

Estrogen

Progesterone

Related Events

Day 1, Menstruation

Low

Low
A few milligram(mg) per day

If pregnancy does not take place, the uterine lining is shed (menstruation), and another monthly cycle starts.

Day 3

Low

Low

GnRH from hypothalamus stimulates the pituitary to send follicle stimulating hormone to the ovary, initiating follicle (egg sack) maturation and thickening of uterine lining.

Day 10

Surge to high

Low

Mature follicle releases estrogen to promote thickening of uterine lining and to stimulate the pituitary gland's secretion of luteinizing hormone that induces ovulation.

Day 14, Ovulation

Medium

Starts to rise
up to 30 mg/day

If ovulation fails, Progesterone is not produced.

Day 24

Drops to low level

Drops to low level

If the egg is fertilized, progesterone from ovary continues to rise. Any drop in progesterone level results in menstruation or miscarriage. Later during pregnancy, the placenta produces up to 3000 to 4000 mg/day of progesterone .

Day 1, menstruation

Low

Low

The drop in estrogen and progesterone level triggers menstruation as well as GnRH secretion in hypothalamus.

After menopause

estradiol: 15% of premenopausal level
estrone: 40 to 50% of premenopausal level

Low

Estrogen still produced in fat, muscle and skin cells by converting androstenedione produced in the ovary and adrenals. Low level of progesterone still produced by adrenals and brain.