There are many types of uterine malformations, including congenital absence of uterus, primordial uterus, uterine dysplasia, double uterus, bicornuate uterus and saddle-shaped uterus, septal uterus, unicornuate uterus and vestigial uterus, etc. 1. Congenital absence of uterus: The uterus is developed from the middle segment of the paramedian tube during the embryonic period, and the vagina is developed from the caudal segment of the paramedian tube. However, the ovaries develop normally. The uterus is extremely small, only 1-3 cm long, with no uterine cavity and no vagina. 3.Uterine dysplasia: also called infantile uterus, also due to the paramedian tubules stop developing when the uterus is not formed. Patients have less menstrual flow and do not have children after marriage. 4.Double uterus: There are two sides of the paramedian tube, under normal circumstances, the two sides will merge to form a uterus and a vagina. When the two sides of the paramedian tube do not merge at all, they will develop into two uterine bodies, two cervixes, two vaginas, and one fallopian tube and ovary on each side of the left and right uterus. Patients usually have no conscious symptoms, and they are mostly discovered during abortion, prenatal examination or even delivery. 5. Bicornuate uterus and saddle-shaped uterus: The bottom of the normal uterus is dome-shaped. If the bottom of the uterus is not fully fused in a bicornuate shape during development, it will form a bicornuate uterus, and some patients may have increased menstrual flow with dysmenorrhea, and when the uterine cavity is narrowed by dysplasia, it may lead to miscarriage or premature delivery during pregnancy; when the bottom of the uterus is slightly sunken in a saddle shape, it is called a saddle-shaped uterus and is mostly asymptomatic. 6, septal uterus: normal uterus has only one cavity, when abnormal development leads to the formation of septum in the uterus, the uterus will be partly or completely divided into two cavities is called septal uterus, prone to infertility, miscarriage, preterm delivery and abnormal fetal position. 7.Unicornuate uterus and stump uterus: If one side of the paramedian tube is normally developed and the other side is undeveloped, it forms unicornuate uterus; if one side of the paramedian tube is normally developed and the other side is underdeveloped, it forms stump uterus. In summary, uterine malformations are mostly caused by incomplete or undeveloped development during the embryonic period.