From a physiological point of view, it is best for women to have children around the age of 20: it is easy to get pregnant, the birth is quick and smooth, the recovery is quick and there are fewer birth defects. Having a baby at this age is really like having fruit on a tree, it will fall down when it is ripe. However, women in this age group are often not mature enough mentally, may not have completed their education, no stable job, so it is not too appropriate to have a child so early. On balance, the more appropriate age to have children is about 25-28 years old, if for career development, it is okay to delay a few more years, but try not to delay until after 35 years old. During the intrauterine period, all the eggs of a female fetus have completed their first meiosis and are thus born with all the egg cells of her life. Her birthday is the “production date” of all her eggs, and just like food, eggs have a shelf life. The quality of eggs that have been in the factory for 20 years and those that have been in the factory for 35 years are not the same, and eggs that have been in the factory for 45 years are basically past their shelf life. Women begin to ovulate after puberty, and as they age, the total number of eggs decreases. In addition, as women age, their eggs age and the percentage of eggs with normal genes decreases. As a result, as women age, their fertility rate decreases, miscarriage rates increase, and the probability of birth defects such as Down syndrome increases. Women in their twenties have normal ovarian function and more healthy eggs, making them more likely to become pregnant, with a monthly pregnancy rate of about 20 – 25%. The probability of miscarriage after pregnancy is about 20% and the risk of Down’s syndrome is about 1/952. Pregnancy in the early 30’s After the age of 30, women’s fertility decreases and their monthly chance of pregnancy is about 15%. Pregnancy over 35 Women over the age of 35 face many problems when trying to get pregnant. the monthly chance of pregnancy for women over the age of 35 decreases significantly, to about 10%. Women in this age group should seek help from a fertility specialist if they are unsuccessful after 6 months of actively trying to conceive. The miscarriage rate is 25% and the risk of Down’s syndrome becomes about 1/378 after the age of 35. The difficulties and risks associated with having a baby after the age of 40 and 45 are even greater.