Why is the wall of uterus thick?

The wall of the uterus is thick due to the presence of three layers of smooth muscle, known as the myometrium:

a) Inner myometrium

a) Middle myometrium

a) Outer myometrium

Functions of myometrium are

1. The outer and inner layers (longitudinal fibers) contract during labor forcing fetus downward and helping in the process of birth.
2. The middle layer of fibers is very thick and arranged into an interwoven network so that contractions in any direction exert equal pressure upon the contents within the cavity.