Ms. Wang, 30, had been married for only 1 month when she did not have her period. She took a test paper by herself and found two red lines – she was pregnant. She and her husband were very happy, and although they were not ready to welcome the baby yet, they were very much looking forward to the healthy growth of this baby. At 50 days of menopause, Ms. Wang suddenly noticed a small amount of coffee-colored vaginal discharge without abdominal pain, she went to the hospital for examination: ultrasound indicated intrauterine pregnancy, the embryo sitting 1.7mm high, and heart tube pulsation was visible. She went to the hospital for examination: ultrasound indicated intrauterine pregnancy, the germ was sitting 1.7mm high, heart tube movement was visible, blood chorionic gonadotropin 5538.0mIU/ml, blood progesterone 20nmol/L. Considering the low value of blood progesterone, the physician suggested progesterone intramuscular injection + Chinese medicine for fetal preservation. One week after treatment, there was still a small amount of vaginal bleeding and no lower abdominal pain. Ms. Wang went to the hospital again for follow-up. The ultrasound showed that the embryo was sitting 3.5mm high in the uterine cavity, the heart tube was pulsating, and an echogenic area of 5.0*10.0mm was seen next to the gestational sac. The vaginal bleeding gradually stopped, and at 60 days of menopause, the blood chorionic gonadotropin 7990.0 mIU/ml and blood progesterone 63.45 nmol/L. At 66 days of menopause, the blood chorionic gonadotropin 10200.0 mIU/ml and blood progesterone 88.10 nmol/L. At 69 days of menopause, the ultrasound showed that the germ structure was seen in the uterus, sitting at 8mm, and no heart tube pulsation was seen. The echogenic area next to the gestational sac was 10.0*15.0mm, suggesting that the embryo had stopped developing. Ms. Wang’s family was sad to know the result, why did the baby stop developing even though they had kept the pregnancy? Li Haiyan, Department of Obstetrics and Gynecology, Wuxi Ninth People’s Hospital, believed that everyone would also feel puzzled after reading Ms. Wang’s encounter: Why did the baby stop developing? The baby starts to grow from a fertilized egg and continues to thrive without four aspects: the baby’s own condition, the mother and father’s side, and environmental factors. According to statistics, 50%-60% of early miscarriages (within 12 weeks of pregnancy) are related to embryonic chromosomal abnormalities, which are often associated with the mother and father. In addition to genetic factors, if the mother is infected during early pregnancy (e.g. TORCH infection, viral flu), has a high fever, takes medication, is exposed to radiation and chemicals (e.g. hair dye), abuses alcohol, smokes, the father’s sperm Abnormalities, early moving into a newly renovated house, etc., can cause chromosomal abnormalities in the baby. Also, the mother’s own chronic diseases such as liver disease, kidney disease, hypertension, diabetes, poor blood sugar control, lupus erythematosus, thyroid disease, polycystic ovary syndrome, hyperprolactinemia, luteal insufficiency can lead to miscarriage, in addition, too frequent sexual intercourse, excessive psychological tension, anxiety, fear and sadness can also lead to miscarriage. This shows that there are so many reasons for early miscarriage. How do we know if the baby is developing well once we are pregnant? The minimum amount of chorionic gonadotropin in the urine is 25 mIU/ml. Dynamic monitoring of chorionic gonadotropin (HCG) can reflect the development of the baby: 100 mIU/ml on the 30th day of pregnancy and 2000 mIU/ml on the 40th day of pregnancy. If the increase is less than 66% within 48 hours, it indicates a poor prognosis of pregnancy. In addition, statistical studies have found that a single blood progesterone level of ≤15.6 nmol/L at 12 weeks of gestation indicates a high risk of embryonic arrest, while a blood progesterone of 78 nmol/L can basically exclude ectopic pregnancy. In this paper, Ms. Wang’s blood progesterone was found to be low at the beginning and she was treated with progesterone to preserve fetus; while the blood β- HCG multiplication was very unsatisfactory and already had a tendency of embryonic dysplasia. At present, all clinical fetal preservation drugs are mainly progesterone supplementation, which is effective if targeting luteal insufficiency, but there is no particularly effective treatment for embryonic chromosomal abnormalities. Any pregnant woman with signs of preterm miscarriage must have an ultrasound to understand the fetus in the uterus prior to fertility preservation treatment. The fetus must be in the uterus and the fetal growth must be consistent with g. Fetal ultrasound growth pattern (menstrual cycle must be normal): vaginal ultrasound on 35 days of menopause can indicate a round or oval gestational sac can be seen in the uterine cavity. At 6 weeks of gestation, the germ and heart tube pulsation can be seen. In normal pregnancy, the gestational sac grows by 1.2 mm per day and the embryonic head-rump diameter (sitting height) grows linearly at a rate of 1 mm per day. In the case of ultrasound where embryonic development has stopped: the average diameter of the gestational sac is >20mm without a germ in the sac, or the head-rump diameter (sitting height) of the embryo is more than 5mm without a heartbeat, the embryo is less likely to survive and a curettage is generally recommended. At present, in the early pregnancy stage, to determine whether the baby is well developed, three indicators are mainly observed: blood HCG, blood progesterone and ultrasound, which must be considered together. This article is authorized by Dr. Haiyan Li.