When the embryo is still developing, the uterus is formed by the convergence of two paramedian tubes, and there is a layer of isolated tissue between the two tubes, which will be absorbed slowly as it develops, so that the uterus can become a normal cavity. If the isolated tissue is not completely absorbed, there is a vertical separation in the middle of the uterine cavity, which is called a Y-shaped uterus. The cause of this condition is still unknown and may be due to genetics (e.g., genetic or chromosomal abnormalities), estrogenic drugs, etc. The Y-shaped uterus is also called a longitudinal uterus because of the vertical separation in the middle, and depending on the length and degree of separation, there are two types of uterus: complete and incomplete. In some cases, patients with a lesser degree of incomplete longitudinal uterus are able to have children normally, but the risk of preterm miscarriage is somewhat higher than in the average pregnant woman and requires increased monitoring during pregnancy. In patients with a completely mediated uterus, it is generally difficult to have a natural pregnancy and the mediastinum can be surgically removed to restore the normal shape of the uterus and allow the uterus to have an intact uterine cavity and be able to have a normal pregnancy. In either case, it is important to have regular obstetric examinations during pregnancy to observe the fetus, placenta and amniotic fluid and to take care of rest.