Menstrual Disorders - Introduction

Typical Menstrual Cycle

Menstrual Phases

Typical No. of Days

Hormonal Actions

Follicular (Proliferative) Phase

Cycle Days 1 - 6: Beginning of menstruation to end of blood flow.

Estrogen and progesterone start out at their lowest levels.

FSH levels rise to stimulate maturity of follicles. Ovaries start producing estrogen and levels rise, while progesterone levels remains low.

Cycle Days 7 - 13: The endometrium thickens to prepare for the egg implantation.

Ovulation

Cycle Day 14:

Surge in LH. Largest follicle bursts and releases egg into fallopian tube.

Luteal (Secretory) Phase, also known as the Premenstrual Phase

Cycle Days 15 - 28:

Ruptured follicle develops into corpus luteum, which produces progesterone. Progesterone and estrogen stimulate blanket of blood vessels to prepare for egg implantation.

If fertilization occurs:

Fertilized egg attaches to blanket of blood vessels that supplies nutrients for the developing placenta. Corpus luteum continues to produce estrogen and progesterone.

If fertilization does not occur:

Corpus luteum deteriorates. Estrogen and progesterone levels drop. The blood vessel lining sloughs off, and menstruation begins.