There are many causes of fetal abortion, besides the quality of the embryo itself, progesterone is an important factor, and estradiol is also particularly important. However, the exact value of the effect varies from person to person. After pregnancy, the development of the embryo is usually determined by the doubling of the hcg and the amount of progesterone. There are no strict rules about what is normal for the first few weeks of pregnancy, but this indicator has a role to play in the normal development of the embryo. In clinical practice, estrogen is required to be on a steady rise, and usually hcg, progesterone and estrogen values are tested several times in early pregnancy to compare and see the quality of the embryo. Generally, in the early stages of pregnancy, an estrogen above 300 pmol indicates a stable embryo. When it reaches 700-800 pmol, there is a germ, and when it reaches 1000 pmol or more, there is usually a fetal heartbeat. After the appearance of a fetal heartbeat, the testing of indicators is mostly relaxed, but if there is a decrease in estrogen, there is also a possibility of fetal abortion. There is no absolute indicator of how much of a drop in estrogen will lead to fetal abortion. If you experience a drop in estrogen, you should be alert to the possibility of fetal abortion, give estrogen supplements in a timely manner, actively preserve the pregnancy and receive treatment. Therefore, early pregnancy tests are very important, and any fluctuation in the indicators will have an impact, so it is important not to take it lightly, and to promptly treat any abnormalities with fertility preservation.