When the segments formed by two chromosome breaks are rejoined by reversing 180 degrees, there is no loss of chromosomal material, but the gene order is reversed, which is called inversion (expressed as inv). If the inversion occurs within the same arm, it is called paracentric inversion; if the two breaks occur in the long arm and short arm, it is called paracentric inversion. Some chromosome rearrangements, such as translocations and inversions, only change the position of genes on the chromosome and do not cause an increase or decrease in the number of genes, thus not producing a clinical phenotype, and are called carriers. Although they are normal, inversion carriers have abnormalities in gamete formation, which can cause miscarriage, stillbirth, and fertility disorders such as children with chromosomal disorders. The interarm inversions that have been identified in our center involve basically every chromosome. Among them, interarm inversions of chromosome 9 are more common, with an incidence of 1% in the population, and it is generally believed that interarm inversions of chromosome 9 may be a normal polymorphism. Individuals with interarmed inverted chromosomes, or inversion carriers, although generally normal in appearance, have structurally rearranged chromosomes after the occurrence of inversions, and during meiosis, when germ cells are formed, they form a unique inversion loop according to the rule of pairing homologous chromosome segments with each other during gamete formation. ). Moreover, after an odd number of exchanges within the inversion loop, four different gametes can theoretically be formed: one with a normal chromosome and one with an inverted chromosome; the other two can form two rearranged chromosomes with partial duplication and partial deletion due to the exchange of the inverted segment with the corresponding segment of another normal chromosome. Each of these two abnormal rearranged chromosomes has a single chromosome, which is a stable aberration and can be passed on to future generations. Therefore, their genetic effects are mainly determined by the length of the duplicated and missing fragments and the lethal effects of the genes they contain. Generally speaking, the shorter the inversions, the longer the duplicated and missing segments, the lower the possibility of normal development of gametes and congeners, and the higher the percentage of infertility, early miscarriage and stillbirths after marriage, and the lower the possibility of delivering abnormal children; while the longer the inversions, the shorter the duplicated and missing segments, the higher the possibility of normal development of gametes and congeners, and the higher the risk of delivering abnormal fetuses. The longer the inversion fragment, the shorter the duplication and deletion, the greater the chance of normal development of the gametes and congeners, and the higher the risk of delivering a malformed fetus. Therefore, it is necessary to strengthen the detection of carriers and prenatal diagnosis of carriers during pregnancy in order to prevent the birth of affected children.