For older mothers of 35 years old to have a second child to overcome four hurdles: difficult to get pregnant, easy to miscarry, more birth defects, high risk of haemorrhage. Difficult to conceive 1. The monthly pregnancy rate of women over 35 years old starts to decrease to about 10%, and the cumulative chance of conceiving in a year is about 75%. 2. Women over the age of 35 who want to get pregnant should consult a fertility specialist if they have not conceived after 6 months of active attempts, and the ability of women over the age of 40 to conceive decreases dramatically. The monthly pregnancy rate is only about 5%, and even with in vitro fertilization (IVF), the pregnancy rate is only 10% per attempt, and the cumulative chance of conceiving in a year for women over 40 is about 40%-50%. This is due to the fact that the number of normal egg cells in the ovaries of women over 40 is greatly reduced. Therefore, women over 40 who wish to conceive should seek help from a fertility specialist if they have not conceived after 3 months of trying. 3. Getting pregnant over the age of 45 is a very difficult task, with less than a 1% chance of getting pregnant on your own, due to the fact that virtually all remaining eggs are genetically abnormal. 4. Almost all successful pregnancies over the age of 45 are the result of donor eggs. Miscarriage susceptibility In the population as a whole, the miscarriage rate is about 15%, and increases gradually with age. 1. At age 35, the miscarriage rate is 25%; 2. At age 40, the miscarriage rate is about 35%; 3. At age 45, the miscarriage rate has reached 50-60%. The most important cause of miscarriage in older pregnancies is chromosomal abnormality of the embryo, so usually there is no point in fertility preservation treatment. More birth defects As a woman ages, the quality of her eggs decreases and the probability of having problems with fertilized eggs increases significantly. At age 35, the risk of Down’s syndrome is 1/378 and the risk of all chromosomal abnormalities is 1/192; at age 40, the risk of Down’s syndrome is 1/106 and the risk of all chromosomal abnormalities is 1/66; at age 45, the risk of Down’s syndrome is 1/30 and the risk of all chromosomal abnormalities is 1/21. And that’s just the This is only the probability of chromosomal abnormalities and does not include the much higher incidence of fetal structural defects. The risk of hemorrhage is high In China, there is no official rate of cesarean delivery, which according to the WHO sample in three Chinese provinces and cities is 46.2%, and according to this analysis is higher than 50% in large cities. Thus nearly half of the women who have second pregnancies have a history of cesarean delivery, and once the placenta of these people is implanted in the lower uterine incision, it is the so-called menacing placenta praevia. The thought of these time bombs makes obstetricians sleep poorly because of the high probability of postpartum hemorrhage from an aggressive placenta praevia, which can lead to hysterectomy in severe cases and maternal death in individual cases.