During copulation (sex) the vagina receives the male penis. The spermatazoa that are ejaculated from the penis make their way up the Fallopian tubes seeking an egg to fertilize. If an ovum (egg) is successfully fertilized by a spermatozoon (a single sperm), it grows into a foetus in the uterus.

The uterus is often known as the womb. It has an inner mucous lining called the endometrium, and a thick wall of smooth muscle called the myometrium.

When not pregnant, a woman's uterus is pear-shaped, and about 7.5 cm long. The upper part of the uterus is connected to the two Fallopian tubes.