Down syndrome is a health condition that requires special considerations.
It is a genetic condition characterised by certain features that are similar in some individuals and that predispose them to other health conditions. It is not a disease in itself but a genetic condition associated with various illnesses.

It has often been stated that maternal age over 35 is a risk factor for having a baby with Down syndrome. However, this condition can occur at any age. In fact, there are no other well-established risk factors documented in the scientific literature.

Down syndrome manifests uniquely in each individual, meaning no two cases are identical. It is important to clarify that there are no “levels”, “degrees”, or “types” of Down syndrome: a person either has it or does not. Genetically, Down syndrome can be classified into three main forms:

1. Free or Regular Trisomy:
   This accounts for 95% of cases. It occurs when, at a very early stage of embryonic development, the chromosomes fail to separate properly, resulting in an extra copy of chromosome 21. This form is more strongly associated with maternal age and is the most common type.
2. Mosaicism:
   This represents between 1% and 2% of cases. In this form, there are two cell lines: one with 47 chromosomes (including the additional chromosome 21) and another with 46 chromosomes. It is sometimes believed that children with mosaicism may have a lower risk of developing certain characteristics or health issues associated with Down syndrome. However, these children also have Down syndrome and should be regarded as such.
3. Translocation:
   This occurs when a fragment of chromosome 21 is attached to another chromosome. This type requires genetic testing of the parents, particularly if they wish to have more children. In such cases, genetic counselling is essential, as one parent may carry the translocation, increasing the likelihood of having additional children with Down syndrome.

Regarding recurrence risk, both free trisomy and mosaicism carry a recurrence risk of less than 1%. However, if the mother is over 35 years old and has already had a child with Down syndrome due to free trisomy, the risk increases due to the additional maternal age factor.

Extreme maternal ages, whether very young or older, are also associated with the occurrence of this condition