What they do know is that the risk of having a child with Down syndrome increases in mothers who give birth at or after the age of 35. The odds are at 1 in 400 by the age of 35 and 1 in 100 at 40.
But here’s an interesting thing: most babies with Down syndrome were born to mothers younger than 35. Experts explain that this is because, statistically speaking, more births happen in younger women.
4. There are 3 types of Down syndrome
One of the significant facts about Down syndrome is that there are 3 kinds. To get a more in-depth idea of these types, we need to know about two other concepts:
- Our chromosomes are in every cell of our body.
- When experts analyze chromosomes (karyotyping), they identify them by number; hence we have chromosome pair #1, chromosome pair #2, up to chromosome pair #23.
Now, here are the 3 types of Down syndrome:
- Trisomy 21 – The most common type occurring in about 95% of Down syndrome cases. Instead of just two, there are three chromosome 21; it occurs in all the body cells.
- Translocation – This accounts for about 4% of Down syndrome cases. It happens when an extra part of or a full chromosome 21 can be found in another pair. For instance, there is an extra chromosome 21 in what was supposed to be pair #14.
- Mosaicism – The rarest type. It happens when some cells in the body have 46 chromosomes, while other cells have 47 because of an extra chromosome 21.
5. There’s no way to “predict” the full impact of Down syndrome on the child
A mother can undergo screening tests to assess the risk of having a baby with Down syndrome; however, these tests (ultrasound, blood tests, etc.) cannot offer a definitive diagnosis.