This chapter focuses on the uterus, a major organ of the female reproductive tract. The uterus is a complex organ due to the evolution of its mechanical properties during the life. These modifications are due to the age, the hormonal changes, the number of pregnancies, and the fact that during any gestation, the size of the uterus is multiplied by more than four. The route of delivery (i.e. vaginal delivery versus cesarean section) may also impact the uterus mechanical properties. All these modifications make that the same woman will have different wombs during her life. Thus, the mechanical properties of the uterus are complex which involves some difficulties to propose an accurate simulation of its mechanical behavior. In this context, we present in this chapter some researches made to simulate the mechanical behavior of the uterus. One of the interest of simulating its mechanical behavior is to improve the knowledge of its attachment system (i.e. ligaments binding the uterus to the pelvis wall). In particular, in this case, the goal is to evaluate damages that could occur during vaginal delivery in order to prevent or to improve treatment of uterine prolapse. The simulation of the mechanical behavior of the uterus could also lead to preventive strategies in order to prevent preterm birth caused by a short cervix. In this case, we have to understand which kind of anatomical changes lead to a cervical shortening. We present two approaches to realize such a numerical simulation of the uterus: the first approach focuses only on the uterus (without considering others organs); the second approach simulates in real-time a vaginal delivery. This latter technique considers all the organs interacting during a childbirth but with a lot of simplifications. The aim is to obtain a correct global behavior and not necessarily an accurate simulation of each organ involved. These two approaches are complementary to achieve realist simulations and to understand the role of each tissue in the pelvic system.