What are the tests looking for?

Antenatal tests check your baby for genetic abnormalities and congenital abnormalities. The most common genetic abnormality tested for is Down’s syndrome and the most common congenital abnormality is spina bifida.

A genetic abnormality is caused by faulty information in the baby’s genes: the fundamental information inherited from parents that programmes the baby to be the unique individual he or she is. The baby’s genes are passed on to him at the moment of conception.

A congenital abnormality is caused by some failure in the growth and development of the baby after conception.

Genetic abnormalities

• Down’s syndrome
• Edward’s syndrome
• Patau’s syndrome
• Turner’s syndrome

You can find more detailed information about these problems in Special Needs.

Down’s syndrome

People who have Down’s syndrome have an extra bit of genetic information in each of their body cells. This causes them to have the typical appearance we associate with someone who has Down’s - short stature, round face, slanting eyes, thick body and limbs. They may also have problems with their heart and lungs.

Down’s can be very severe, with some children having an IQ as low as 40, while other children will be much less seriously affected and can eventually lead almost independent lives. It’s fair to say, however, that Down’s is more often a cause of severe learning disability than mild.

Edward’s syndrome, Patau’s syndrome

Other genetic conditions which antenatal tests such as chorionic villus sampling and amniocentesis can diagnose, are Edward’s and Patau’s syndromes. Like Down’s, these conditions are caused by the baby having extra bits of genetic information. They are much rarer than Down’s and children born with them generally die within the first two years of life.

Turner’s syndrome

Turner’s syndrome affects only girls. These babies have faulty sexual genetic information in their cells.

Congenital abnormalities

• Spina bifida
• Hydrocephalus
• Anencephaly
• Gastroschisis and exomphalos

You can find more detailed information about these problems in Special Needs.

Spina bifida

Babies born with spina bifida have a gap in the bones of their spine so that the spinal cord which lies underneath is exposed and damaged. There are varying degrees of spina bifida and some people have only very minor symptoms. Others have much more serious problems.

Hydrocephalus

Spina bifida often goes hand in hand with hydrocephalus. This is the term used for excess fluid on the brain which can lead to brain damage. An operation is usually needed soon after birth.

Anencephaly

Anencephaly is a congenital condition where the baby’s skull does not form properly and her brain may not develop at all. These babies (nearly all girls) cannot live for long after birth.

Gastroschisis and exomphalos