You can still get an ultrasound at 12 weeks and request that the NT measurement is not taken.

Eggs and sperm usually contain only one copy of each chromosome. Down syndrome occurs when either the egg or sperm has an extra copy of chromosome 21. When the egg and sperm combine, the 'baby' will then have 3 copies of chromosome 21. Having no family history of Down syndrome does not mean that a child will not have it.

As women get older, their eggs are more likely to have issues when they separate and not split evenly, and the egg may have an extra or a missing chromosome. This is why the chance of having a child with down syndrome is higher as you age. There is still possibility of this occurring in younger women.