Recently, many patients have come to genetic counseling with chromosome reports in their hands, “Doctor, what do I think about this chromosomal abnormality result? Is it possible to have children? Is there any effect on the offspring?” After a closer look, the majority of the patients’ chromosomal results are the result of a chromosomal polymorphism. Figure 1 Normal male karyotype results (G bands) What is a chromosomal polymorphism? It is generally accepted that chromosomal variants often cause disease. However, it has been found that in some normal people, there are also variations in specific chromosomal positions, which are called polymorphic variations. Figure 2 Common karyotypes of chromosomal polymorphisms What are these chromosomal polymorphisms related to? Current research has found that these chromosomal polymorphisms may be associated with a history of poor maternal outcomes, recurrent miscarriages, and sporadic infertility. Some researchers have also found an association with psychiatric disorders. However, most of these are based on retrospective statistical analyses, and none of them can explain their association, and the pathogenic mechanisms are unclear. What is the relationship between chromosomal polymorphisms and infertility? It has been found that chromosomal polymorphisms are more prevalent in the infertility population than in the normal group, especially in primary female infertility and male infertility, and in male infertility it is common in patients with azoospermia, oligospermia, and teratospermia. For patients requiring assisted reproductive technology for treatment of infertility, several studies have shown that chromosomal polymorphisms are not associated with IVF-ET (in vitro fertilization-embryo transfer) treatment outcomes (including embryo quality, implantation rate, clinical pregnancy rate, early miscarriage rate, and continued pregnancy rate). Some studies have found that considering the association of male chromosomal polymorphisms with spermatogenesis, couples who fail first-generation IVF treatment are recommended to undergo direct treatment with intracytoplasmic single sperm injection (ICSI) assisted reproductive technology in the next cycle, which is more beneficial for fertilization rates. Why does chromosomal polymorphism arise? Can it be inherited? Chromosomal polymorphisms can occur due to genetic predisposition and are also thought to be associated with stressful stimuli. Can chromosomal polymorphisms be cured? How can I plan for future generations? Chromosomal polymorphisms are alterations in the genetic material and there is no gene therapy or medication available for this part of the disease. Because they are present in some normal people and do not cause major diseases or effects, and because the cause of infertility is not clear, it is not recommended that patients undergo preimplantation genetic diagnosis to treat them. For infertility patients who come to the fertility center, solving the fertility problem is a top priority. If one partner carries a chromosomal polymorphism, there is a 50% chance that it will be passed on to the offspring. While the offspring may not necessarily develop similar diseases due to chromosomal polymorphisms, prenatal/postnatal chromosomal testing and diagnosis and follow-up observation can be considered to avoid additional chromosomal variants associated with advanced childbearing.