Estrogen plays a rather important role in the maintenance of pregnancy. On the one hand, it plays an important role in the preparation of the endometrium before embryo implantation and the maintenance of the luteal phase; on the other hand, it promotes the synthesis of progesterone by the corpus luteum and placenta, which facilitates the stabilization of the intrauterine environment and maintains the development of pregnancy. The rapid rise in E2 levels in early pregnancy reflects the quality of the dominant follicle and the function of the corpus luteum of the ovary, and the rapid rise in E2 levels reflects a good functional unit of the fetal placenta and its survival. It has been found that although some patients have primitive ventricular pulsations detected by ultrasound, those with low E2 levels tend to have a poor prognosis. Therefore, the use of estradiol or estradiol in combination with other clinical indicators as a means of monitoring early pregnancy has some clinical significance.