What factor is linked to the increased incidence of Down syndrome?

The association between advanced maternal age and an increased incidence of Down syndrome is well established in medical literature. As women age, particularly those who are 35 years and older, the risk of chromosomal abnormalities, including Down syndrome, increases significantly. This is thought to be related to the age of the oocytes (egg cells), which may exhibit more chromosomal abnormalities as women age. The risk becomes increasingly pronounced with advancing age due to factors such as changes in the cellular processes of oocyte development and the duration of exposure to potential environmental risk factors over time.

In contrast, while maternal smoking, low socioeconomic status, and genetic predisposition can influence various health outcomes during pregnancy, they are not specifically linked to the increased risk of Down syndrome in the same direct manner as advanced maternal age. Maternal smoking can adversely impact fetal development but does not have a direct correlation with chromosomal abnormalities. Socioeconomic status may affect access to care and overall health but is not a direct cause of Down syndrome, nor is genetic predisposition a specific risk factor for the majority of cases, which arise from nondisjunction events during meiosis rather than inherited genetic traits.