Estradiol can make the endometrium grow because the growth of the endometrium depends on estrogen and progesterone. Normally, the ovaries secrete estrogen and progesterone periodically to mediate the thickness of the endometrium, so that the endometrium will shed and eventually menstruate. It is important to use the medication under the guidance of a doctor, because there are reasons for the thin endometrium, which may be caused by the lack of estrogen, or by other causes, such as incomplete adhesions of the uterine cavity, which can also lead to thin endometrium.