Since the reference value of estradiol after pregnancy may vary from one test department to another, but generally in early pregnancy, estradiol is considered to be normal as long as it is above 700 pmol/L. In early pregnancy, the ovaries usually secrete estradiol to indirectly stimulate the normal growth and development of the embryo, but since the embryo itself does not secrete estradiol, the level of estradiol at this time is mainly determined by the endocrine function of the ovaries, not by the quality of the embryo itself. The quality of the embryo itself is determined by the chorionic gonadotropin (i.e. HCG), so in early pregnancy, the ovarian secretion of estrogen will generally be at a higher level, which is why it is above 700 pmol/L. However, since the reference value and the units of each test department may vary, at this time, the specific reference standard should be compared according to the reference standard of the test department, but in most cases it is above 700 pmol/L or more, and some may exceed a thousand, but some test departments may also be around 500 pmol/L. Therefore, it is not possible to determine the specific situation of pregnancy based solely on the value of estradiol, but rather the growth and development of the embryo should be determined by a combination of chorionic gonadotropin (HCG) and progesterone.