I. Age cut-off line for advanced fertility Generally speaking, the chances of conception begin to decline after 30 years of age, but only slowly before the age of 35, while the rate of decline in fertility accelerates after the age of 35, so the age of 35 is used as a cut-off line for advanced age. Second, the risk of advanced age 1, fertility decline Foreign statistics show that the fertility of women at the age of 35 is only 50% of that at the age of 25, and then drops to 50% of that at the age of 35 at the age of 40. 2.Increased risk of genetic diseases in the offspring Increased risk of Down’s syndrome and other genetic risks. 3. Increased risk of complications during pregnancy The risk of miscarriage during pregnancy increases from 12% at age 30-35 to 18% at age 35-39. Increased risk of preeclampsia, anemia, gestational diabetes, weak contractions, postpartum hemorrhage and intrauterine growth retardation, and preterm birth during pregnancy. Fertility assessment and pregnancy guidance Women older than 35 years old should undergo fertility assessment before conception, in addition to routine preconception examination, sex hormone and male semen examination should be done to understand ovarian function and male fertility function. Once pregnant, eugenic counseling and prenatal diagnosis are recommended, and non-invasive prenatal diagnosis, Down screening, amniocentesis, etc. can be chosen according to the situation.