Gordon and Sarah Brown were fortunate that their latest baby, Fraser, was born in Scotland, where all newborns are tested for cystic fibrosis. In England the practice is not yet universal, and nor can all parents of CF children be guaranteed that their baby will be cared for in a specialist unit. England needs to catch up with Scotland and make this test universal.

The American College of Obstetricians and Gynaecologists has recently recommended that all American pregnant mothers should be tested. In good British maternity units mothers should be offered an ultrasound scan when they first book in between the 11th and 13th week.

In any decent unit the scan will include the nuchal translucency test. This measures the thickness of the nuchal fold, the tissue at the back of a baby’s neck.

If a baby has Down’s syndrome, extra fluid accumulates in the fold and its thickness increases beyond 3mm (0.1in).

Increased thickness does not necessarily mean that the baby has Down’s syndrome, but it is an indication that further tests are needed. These would involve either amniocentesis, examination of the fluid around the baby, or chorionic villus sampling, taking a specimen from the placenta.

I always used to encourage my patients to have a blood sample taken at the 16th week to test for alpha foetoproteins, as do most respected units. If these are abnormal, further scans are recommended because unusual alpha foetoprotein levels may indicate trouble ahead. Too high a level may reveal an increased chance of spina bifida or abnormalities of the skull, and a very low reading may indicate Down’s syndrome.