What defines a major risk factor for Down syndrome associated with maternal age?

The association between maternal age and the risk of Down syndrome is well-established, particularly highlighting that advancing maternal age is a significant risk factor. Women who are 35 years old or older at the time of delivery have a notably higher incidence of having a child with Down syndrome compared to younger mothers. This increased risk is thought to be related to the age of the mother’s eggs and the mechanisms involved in cell division during meiosis.

As women age, the likelihood of chromosomal abnormalities during egg formation increases, leading to a greater chance of conditions such as Down syndrome, which is caused by the presence of an extra chromosome 21.

In contrast, maternal ages younger than 16 years do not have a similar elevated risk for Down syndrome. Additionally, while family history of Down syndrome and a history of genetic disease can be relevant in a broader context of genetic counseling, they are not considered primary risk factors linked to maternal age in the same way that being older than 35 years is. This distinction emphasizes the crucial role of maternal age as a specific factor in the epidemiology of Down syndrome risk.