Since the country opened up to two children, from time to time, middle-aged women over 45 years old come to the clinic to ask for advice on having a second child and to check if they can get pregnant, mostly because their husbands are forcing them to. I can only tell her to let nature take its course, there is really no need. Not to mention the physical damage, think about the time to enjoy the birth of a child, bring up a child, the previous days of chicken and dogs again, you feel the joy of life are gone. A few years ago I jokingly asked my son, who was in college, “If my mother has a younger brother or sister, he or she will only be 10 years old when I retire at 60. The son was silent for a while before he said, “I still have my own wife and children to raise by then.” I couldn’t help but laugh at the son’s truthfulness, how much of a burden is it on the existing family to have one more child? At least for the first child is not fair. In fact, from the perspective of eugenics, the best age for women to have children is between 23 and 30 years old. This is because women at this age are fully developed in all aspects of their bodies, have high quality eggs, and are mature in terms of psychological development. The conception rate is high, the vitality is vigorous, and the pregnancy can create a good environment for the fetus to conceive, which is conducive to the development and growth of the fetus, and most of the babies are healthier and smarter. And during the delivery process, the physical strength is good, which is conducive to the smooth delivery of the fetus and reduces the rate of cesarean delivery. Postpartum recovery is quick, so you have the energy to nurse your child and ensure that your baby grows healthy. 11 to 19 years old is still in adolescence, reproductive organs, endocrine, physical development, and psychological immaturity. Premature childbirth is detrimental to physical and mental health, and can easily lead to increased maternal mortality. The reason why the rate of obstructed labor is particularly high among women in ancient times is that the body is not mature because the age of childbirth is too early. Some data show that the incidence of congenital infantile stupidity is only 1 in 1,500 between the ages of 23 and 30; 1 in 900 between the ages of 30 and 34; 1 in 300 between the ages of 35 and 39; and up to 1 in 40 over the age of 45. This means that the older the age, the higher the risk. Therefore, over the age of 35, we call it advanced maternal age, when ovarian function begins to decline and the chance of pregnancy decreases, and the rate of malformation is high. Even when pregnancy occurs, there are increased pregnancy complications and comorbidities. The number of primordial follicles in the ovaries is constant, from approximately 1 million follicles at birth to only 1 to 200,000 in adulthood. The number of primordial follicles reflects the reserve of the ovary and is called the “follicular pool”. From puberty onwards, a portion of the follicles develop on both sides of the ovaries with each menstrual cycle, but only one follicle is mature enough to be the dominant follicle, and when it reaches 18-20mm, it expels the egg from the ovary. Each menstrual cycle, some of the primordial follicles are stimulated, and the number of remaining primordial follicles decreases, and around the age of 50 there are almost none left, and the capacity of the follicular pool becomes smaller and smaller, finally entering the menopausal state. Data show that the incidence of infertility is 1/7 and age is one of the main factors leading to infertility, with fertility decreasing after the age of 35 and pregnancy being rare after the age of 45. The number and quality of mature follicles in older women decreases significantly, and the older they are, the fewer eggs they produce each cycle, and even if they do get pregnant, the quality is not always good. Not only is it difficult to get pregnant at an advanced age, but the miscarriage rate is also high. The quality of eggs or fertilized eggs also decreases due to environmental factors, mental stress, etc. The miscarriage rate is low before the age of 30 for women, and can increase to 20% after the age of 35 and up to 40% after the age of 40, indicating that the poor quality of embryos leads to a high miscarriage elimination rate. In addition, the chances of combined gynecological diseases in older women are much higher than in younger women, such as endometriosis, uterine fibroids, myometriosis, as well as heart disease, diabetes and kidney disease, all of which may lead to miscarriage. A few suggestions: 1. For women of childbearing age who wish to have children, have them between the ages of 23 and 30 if possible. 2. Women with comorbidities such as uterine fibroids, myometriosis, endometriosis, etc. should go for a trial pregnancy as early as possible. If you are almost 35 years old, go for IVF assisted reproduction in time. 3. Do what you do at what age and plan your life with purpose. You can work during pregnancy, like we medical professionals are working until delivery. 4. For those who have been found to be infertile, do not delay childbirth after 1 to 2 years of fruitless attempts to conceive. Don’t take a detour and decide to do IVF as early as possible. The younger the age, the higher the success rate and the less the cost.