Estradiol decline less than 20ng/ml will generally have the risk of fetal arrest, but the specific decline to what extent will cause fetal arrest, can not simply look at the value of estradiol, resulting in fetal arrest on the one hand, due to chromosomal factors, on the other hand, due to luteal insufficiency, progesterone value is too low. In the early stages of pregnancy when the growth and development of the fetus is unstable, regular review of the six female hormones and progesterone values and other tests to ensure that the indicators in the normal range, the value of progesterone is too low to timely oral or intramuscular injection of progesterone, to protect the fetus to prevent the birth of an accident. At the same time, the uterine adnexa ultrasound should be regularly rechecked, the gestational sac does not develop or gradually shrinking also has the risk of fetal arrest.