1, the impact of childbearing age on the fetus Physiologically, the female reproductive organs generally develop gradually after the age of 20, while the whole body bones such as teeth calcification, wisdom teeth, etc. can not be completed until after the age of 23. The development and maturation of male reproductive function is later than that of females. Therefore, if you get married too early and have children, the mother’s body is rapidly developing and cannot supply the fetus with the nutrients needed for growth and development, such as protein, carbohydrates, vitamins, inorganic salts, trace elements, etc., which can affect the physical and intellectual development of the fetus. At the same time, the sperm produced by men in early marriages and early childbirth is low in quantity and quality, and prone to sperm mutilation and chromosomal abnormalities, which is obviously not conducive to embryonic development and affects eugenics. The best age of conception for women is 23-29 weeks old. The best age for a woman to conceive is 25 to 30 years old, and there are more problems once you get pregnant around the age of 20, because you are young and do not have the ability to be a mother, neither self-protection nor childcare; secondly, the economy is not yet independent and you have to rely on your parents. If the unmarried pregnant first is more difficult, often afraid to reveal the truth for help, often resulting in nutritional deficiencies, resulting in the birth weight of the newborn baby decreased and affect the physical and intellectual development, or due to poor maintenance and a variety of unexpected problems. The best age for first pregnancy should not exceed 30 years old. This is because before a woman is born, her egg cells are stored in her ovaries, and if she becomes pregnant too late, her eggs will be too old and will be more affected by environmental pollution, making them susceptible to chromosomal aging, leading to a higher rate of malformations. At the same time, because of the reduced elasticity of the birth canal in older mothers, it is easy to prolong labor and surgical assistance in childbirth, which inevitably also affects the health of the fetus to a certain extent, according to statistics, the incidence of congenital stupid fetus is 1/5000 in mothers aged 25-29 years; 1/1800 in mothers aged 30-40 years; 1/900 in mothers aged 35-39 years; and in mothers aged 45 years or older This shows that there is a relationship between a woman’s age at childbirth and the health of the fetus. Similarly, when men marry at an older age, the genetic mutation rate of sperm increases accordingly, and the quantity and quality of sperm are not guaranteed, which is also very unfavorable to the health of the fetus. It is believed that the father’s age at childbirth is related to the occurrence of congenital stupidity, and it is even believed that 25% of congenital stupidity patients are caused by the father’s side. Therefore, from the perspective of eugenics, it is inappropriate to have children too early or too late. The best age for women to marry and raise children is after the age of 23, which is the most favorable age for future parents in terms of work, study, health, economic strength, physical strength, and energy.