The critical risk is a result of mid-term Down’s syndrome screening, which indicates that the baby may have Down’s syndrome, but the probability is very low. The reasons for the critical risk of Down’s syndrome screening are: 1. it may be related to the age of the pregnant woman, poor ovarian function, aging eggs, etc. 2. the accuracy of the screening results may be affected by overwork, poor rest and emotional changes before the screening. 3. the results of Down’s syndrome screening are related to the pregnant woman’s age, actual weight, gestational week, etc. if the information provided by the pregnant woman is not accurate, it may also affect the screening results and the critical risk. If the information provided by the pregnant woman is inaccurate, it may also affect the screening results and result in a critical risk. The screening result of critical risk does not mean that the fetus has a problem. To further confirm the diagnosis, non-invasive DNA testing can be considered.