Today's women think about motherhood at an older age. The best time for natural pregnancy is the mother's age from 19 to 30 years. During this period, nature provides a woman with many fully-developed eggs. After 30, the number of follicles gradually decreases, and the quality of the eggs is no longer so good. At 33, fertility rapidly decreases - there is only a seventh of the reproductive potential that a woman receives at birth. Of course, in addition to this, there are other cases in which doctors recommend using only donor eggs. For example, genetic diseases of the intended mother. Before the procedure, fertility doctors carefully examine the egg donors. An oocyte donor must have healthy children and have a compatible blood type, Rh factor, general characteristics of health, and physique are also taken into account.