“Doctor, when I was pregnant with my oldest child, it went very well, but now I want to have a second child, so I’m afraid to get pregnant again. Ms. A anxiously told the doctor about her “experience”. The doctor said that Ms. A, 35 years old, had a natural pregnancy at the age of 25 and gave birth to a girl without any problems. She wanted to have another child after the national policy of two children was liberalized. She had three spontaneous miscarriages or embryonic abortions at about 2 months of pregnancy, and had to undergo surgery to remove the embryo. Later, I was afraid to have another natural pregnancy because I was afraid of having another miscarriage. The doctor did some screening for the cause of miscarriage, in which both sides chromosomes, were normal. Of course childbirth is not the responsibility of the mother alone, the father’s feelings are also the same, right? A young father, 32 years old, athletic and in great shape, whose wife had two miscarriages and a healthy child between them, came to see the doctor and had his sperm checked and his chromosomes found: 46, XY, t(9:22), why? How can chromosomes have problems when you have given birth to a child? 1, the causes of spontaneous abortion (1) embryonic chromosomal abnormalities: many people think that the parents’ chromosomes are normal, the fetus will not be abnormal, in fact, it is not. Among the many causes of spontaneous miscarriage, the first one is still embryonic chromosomal abnormalities, according to the literature, accounting for about 50-60%. (2) Chromosomal abnormalities in both or one of the parents: Because there are many types of chromosomal abnormalities, it is possible to have a healthy child in this case, but the odds are against it. (2) Both parents or one of them have chromosomal abnormalities: Because there are many types of chromosomal abnormalities, it is possible to have a healthy child in this case, but it is only a matter of chance. (3) It is important to have children before it is too late: as we get older, the chance of chromosomal aneuploidy increases. Chromosomal aneuploidy is mainly caused by the non-separation of chromosomes during gamete formation. According to the analysis of foreign big data (more than 10,000 cycles of PGS data): the proportion of healthy embryos under 35 years old is 1/2; the proportion of healthy embryos between 36 and 40 years old is 1/3-1/4; the proportion of healthy embryos between 41 and 44 years old is 1/6-1/8; the proportion of healthy embryos over 45 years old is 1/10. (4) Other factors: immune factors, endocrine factors, anatomical factors are also causes of (5) It is especially noted that some people worry that assisted reproductive technology treatment will increase the miscarriage rate. According to the literature, a comparative analysis of the incidence of chromosomal aneuploidy in embryos after natural pregnancy and assisted reproductive technology treatment suggests that the incidence of chromosomal aneuploidy in embryos aborted by different pregnancy methods is not statistically significant. 2.Miscarriage has occurred, what should be done next? (1) Embryonic chorionic villus chromosome examination: Nowadays, many miscarried couples have checked their chromosomes and refused chromosome examination of miscarried chorionic villus. After reading the above analysis, I hope the couple who miscarried can understand. Especially with two or more miscarriages, chromosomal examination of the embryos for the chorionic hair will help to find the cause of the disease and facilitate the guidance of eugenics for another pregnancy. (2) PGS or PGD (often referred to as third generation IVF) ① PGS is used to detect the aneuploidy of embryos and select embryos with normal chromosome numbers for transfer. For example, in the case of Ms. A in the article, we recommend the next step of PGS after excluding other causes of miscarriage; ② PGD is to detect whether the embryo carries genetic defects, which is applicable to abnormal chromosome structure (chromosome translocation, Y chromosome abnormality, etc.) or single gene disease (α, β thalassemia, etc.); for example, the father in the article belongs to chromosome balance ectopic, we recommend the next step of PGD program.