According to the table of risk of having a down syndrome baby by maternal age, it indicates that the chance of having a child with down syndrome increases with female’s age.
The older female, the greater risk of having a child with down syndrome. Although the risk can happen at any age but the younger mothers are at the lower risk than the older mothers.
For example, women at age 28, the risk of having a child with down syndrome is 1 in 1000 referred to the table. Compared with women at age 40, the risk is 1 in 100 accordingly.
The causes are still not clear. According to the study, the group of young mothers who have a child with down syndrome (trisomy 21) struggle with one risk factor. Which is the lower chromosomal crossover amount in every pair of chromosomes compared with normal people. Siblings have similar characteristics. So that low genome-wide recombination rates might be a reason of down syndrome incidence in this group. (As a result of the genetic abnormality happened to some genes, e.g., RNF212, MSH4, MSH5, TEX11 that play a role in meiotic recombination.) The other cause of down syndrome may come from a chromosomal translocation.
Young women with family history of down syndrome should plan for having a baby by attending chromosome testing on both husband and wife. Moreover, Preimplantation Genetic Screening (PGS) using Next Generation Sequencing (NGS) technique will be needed.
Reference: Prime Fertility Center Co., Ltd.