Pregnant women are generally registered with the obstetrics department for Down’s syndrome screening, or with the obstetrics and gynecology department if the local hospital does not have a breakdown. The results are usually available in about 1 week, mainly through blood sampling to detect the concentration of alpha-fetoprotein, chorionic gonadotropin and free estriol in the mother’s serum, and combined with the pregnant woman’s due date, age, weight and the week of pregnancy when the blood was taken. The risk factor for Down’s syndrome and neural tube abnormalities is determined by taking into account the mother’s due date, age, weight and week of gestation at the time of blood collection. It is recommended to fast during the Down’s syndrome screening test to avoid food disturbances that may affect the accuracy of the Down’s syndrome screening results. Generally speaking, the older the pregnant woman is, the more likely the fetus will be sick. For example, if a woman is over 35 years old, her ovarian function will gradually decline, the quality of her eggs will also decrease, and the probability of embryonic chromosomal abnormalities will increase, which is a high-risk group. Down screening is not recommended, and further consultation is needed on whether to do non-invasive DNA or amniocentesis for karyotype analysis.