A tilted uterus refers to the position of the uterus in the abdomen as it relates to the bladder and the rectum. Most women have their uterus tilt towards the bladder (anteverted) but about 20% of women have it tilting toward their rectum (retroverted). Years ago, we used to believe that it led to infertility but we now know that it does not. Sex can be uncomfortable in certain positions because the ovaries also shift toward the front making it painful on deep penetration. Trying a new position usually remedies the problem.
Very rarely, in a patient that has a tilted uterus toward the rectum (retroverted), when pregnant (only in the first 12 weeks), the uterus can get "stuck" and cause discomfort. With a simple visit to your physician, they can correct it by using a special device called a pessary. It elevates the pregnant uterus until it gets bigger and grows out of the pelvis. The pessary can then be removed.