What causes the uterus to become tilted?
A so-called "normal" uterus is typically straight up and down or tilted slightly toward the stomach. A tilted uterus (sometimes called a "tipped" uterus) refers to one that tilts backward toward the spine.
It can be caused by several factors. Sometimes, as a girl grows and develops into a woman, the uterus may not move into a forward position (ideal for conception). This is a common conclusion for women who discover they have a tilted uterus when they have trouble conceiving their first child. Childbirth is the second cause of a tilted uterus. Generally, if a child is conceived, childbirth can correct an already tilted uterus, making conception easier after the first time. In some cases however, childbirth can cause an otherwise "normal" uterus to tilt backward and complicate future conception. Finally, a tilted uterus can be caused by scar tissue - usually the result of endometriosis or fibroids.
I think in most cases, women do not even know their uterus is tilted until they have trouble with conception. Modern medicine has made conception possible, however, in such cases, and the problem often resolves itself.