1, fertility and the age of women related to women’s fertility age is more important than men, the best age for women, according to medical practice and a large number of treatment analysis, that 24-29 years old is the best age for women to have children, because female fertility is related to the number of follicles stored in the ovaries, women in the mother’s womb at 20 weeks the number of basic follicles about 7 million, after the birth of the newborn stage about 2 The number of follicles in a woman’s ovaries is estimated to be 400-500 during her lifetime, and if she ovulates once a month for 12 months a year, it is estimated that she can have menstruation for 30 years, and if she has menstruation at the age of 15, it is estimated that her fertility can be maintained for 20-30 years. Most women who have a second baby are around 35 years old, so their fertility is already significantly reduced, and some women even experience menopause before the age of 40. The age of the female ovaries represents the function of fertility, clinically the hormones follicle stimulating hormone and estradiol are used to indicate the function of the ovaries, if follicle stimulating hormone is between 5-8miu/ml, it means the ovaries are functioning well and have the ability to bear children, the higher the follicle stimulating hormone means the older the ovaries are, the lower the fertility, if follicle stimulating hormone is >40miu/ml and estradiol is <40pg/ml, it means the ovaries are functioning well and have the ability to bear children. If follicle stimulating hormone >40miu/ml and estradiol <40pg/ml, it means that ovarian function has reached the level of menopause, which we call premature ovarian failure, manifested as irregular menstruation or even amenorrhea, easy sweating, irritability and other symptoms of menopause, it is very simple to go to the hospital to check the reproductive hormones in the blood for a clear diagnosis. The author's experience is that early ovarian failure, some patients early detection, active treatment is possible to have a chance of pregnancy, or even full-term delivery, but if the disease is delayed, not timely diagnosis, not treated, premature ovarian failure becomes irreversible, that is, the woman lost the opportunity to have children. Therefore, we hope that women must care about their menstruation, and once they have menstrual disorders for 3 consecutive months, they should seek medical attention in time to avoid delays and lifelong regrets! 2, sperm abnormalities Successful pregnancy is inseparable from the quality of the male partner's sperm. The best age for men to have children is 25-36 years old, and there is evidence that men have the best quality of sperm and the strongest vitality of sperm at the best reproductive age, and if men are too old to have children, the children born have a higher incidence of congenital malformations and hereditary diseases. Sperm abnormalities can be manifested in the reduction of the volume of one discharge, the reduction of the proportion of sperm moving forward, and the concentration of sperm can also appear to be reduced, thus manifesting in the reduction of the male partner's fertility. 3, the female party appeared gynecological diseases With the increase in age, the female party appeared gynecological diseases, such as uterine fibroids, about 1/3 of women of childbearing age combined with uterine fibroids, and growing; chronic pelvic inflammatory disease, while the complication of tubal inflammation, resulting in tubal obstruction; ovarian cysts, can also be combined with endometriosis, all these gynecological diseases can affect pregnancy. 4, the complications of contraception on the female side The placement of birth control ring, easily caused by inflammation or obstruction of the fallopian tube, if the contraception fails, frequent scraping, there may be the possibility of endometrial damage or uterine cavity adhesions, thus leading to the destruction of the functional layer of the endometrium, causing a reduction in the blood supply to the endometrium, the embryo is not easy to bed. In case of abnormal pregnancy, such as ectopic pregnancy, if the abnormal pregnancy occurs in the fallopian tube, there is a possibility that one of the fallopian tubes may be removed and the chance of pregnancy may be halved because one tube is missing, and also the function of the ovary on the same side may be reduced because the blood supply around the removed tube is reduced. Recently, we met a patient who was infertile 1 year after removal of the birth control ring. 5, environmental pollution: air, diet, water quality The current environmental pollution to its serious extent, PM2.5 exceeds the standard, industrial development of toxic substances, such as endocrine disruptors, organic solvents, pesticides, heavy metals, etc., not only affects people's health, but also endangers the human reproductive function, endangering the female ovaries, male testicular organs, human reproductive organs for food The human reproductive organs are sensitive to food pollution dioxins, xylene in the decorated rooms, which affects our life in Shanghai Oriental Hospital Reproductive Medicine Center Yang Fan all the time, in addition to dietary insecurities, water pollution and so on these unfavorable factors can affect fertility. 6, work pressure and change in lifestyle habits The work pace of modern society is accelerating, young people are under too much pressure, excessive alcohol consumption, smoking and beverages, can affect our health. The popular application of computers and cell phones bring us convenience while also damaging our bodies, poor self-discipline can be obsessed with video games, staying up late, looking down at the cell phone people, etc. are prone to head and neck diseases, while the change in habits of geeks and nerds can also affect fertility function. 7, the number of married life reduced due to busy work, couples get together less and more often, due to stress, physical and mental exhaustion, resulting in a reduction in married life, generally speaking, couples 35-40 years old should ensure the frequency of 1-2 times a week of married life, which is also the cause of the second baby does not come. 8, the impact of the first baby's upbringing on the second baby The first baby needs to be raised and educated, and the reasonable distribution of work and household chores in the family is an influencing factor. 9, the impact of the second baby on family life and economic pressure Already have a baby, whether to have a second baby, whether the second baby affects the quality of family life, whether the children's education costs can afford which? All of the above are various reasons that affect the delay in the second baby of each family, I hope that the family ready to have a second baby, timely pre-conception examinations to the hospital, early detection of problems, early consultation and preparation for the birth of the second baby, so that each family with the conditions to have a second baby, the icing on the cake to create another success, the early realization of the family of four people in the world.