Q: what causes Down syndrome?
A: despite decades of research, the exact cause of Down syndrome, what makes the number 21 chromosomes stick together, has eluded discovery. Many factors are considered to be possible causes, age of mother is the only factor related to likelihood of having a baby with Down syndrome that has been proven. The process of meiosis in eggs starts while a woman is still a fetus herself and it is possible that as they remain suspended in their meiosis for many years that something happens to cause the chromosomes to become sticky or fail to separate properly. Research has supported the view that older eggs are more prone to errors in cell division with increasing maternal age. Having said that, babies with Down syndrome are born to mothers of all ages and over half of babies with DS are born to mothers who are under 35. This is because women under 35 make up the majority of the child-bearing population. There is currently no clinical evidence that anything the mother or father does before or during pregnancy causes DS.
