Down's Syndrome

What Is It?

Down's syndrome is caused by the presence of an extra chromosome. Normally, babies are born with 23 pairs of chromosomes, 46 chromosomes in total in every cell in our body. In Down's babies an extra copy of chromosome number 21 is produced the embryo forms. Due to this, Down's syndrome can also be known as trisomy 21.

Will My Down’s Baby Suffer Any Particular Medical Conditions?

Down’s babies can be more susceptible to the following medical conditions:-

• chest and sinus infections
• dry skin,
• difficulty feeding
• problems keeping their body temperature stable
• learning disability. Down’s children learn more slowly than other children of their age
• heart problems ranging from minor heart murmurs to more serious abnormalities
• mild to moderate hearing loss is much more common in Down’s children
• visual problems such as squints and long and shortsightedness
• GI problems, for example constipation
• Reduced life expectancy of around 50 years

Will I Recognize A Down’s Baby?

A Down’s baby has recognizable physical features, that might include a flat face, a large tongue and slanting eyes and broad hands with little fingers that curve inwards.

I’m An Older Mum – Are My Chances Of Having A Down’s Baby Increased?

Yes. The chances of having a baby with Down's syndrome increase as you get older. 1 in 2000 births from teenage mothers are affected by Down's syndrome, a 48 year old mum has a ten per cent chance of giving birth to a Down’s baby. However, 80% of babies with Down's syndrome are born to women under 35, since these women account for the majority of the childbearing population.

There is no known link between Down’s and social class, race, preparation before, or behaviour during pregnancy.

Which Scans Will Test For A Down’s Baby?

There are no tests that can give a definite yes or no answer. Screening tests are available that can help parents assess the risk of their unborn child having Down's syndrome. The age of the mother is used with blood tests and scan results to calculate the risk specific to her. If these tests indicate a higher risk pregnancy (usually taken to be a 1 in 250 chance or greater), the results can be verified with tests known as diachorionic villus sampling and amniocentesis. Information about these is included below:-

• Blood tests - a screening test is usually done for mothers who are at increased risk of having a baby with Down's syndrome (usually older women) at 15-22 weeks of pregnancy. There are four “substances” that can be indicative, so the tests are known as the "double", "triple" and "quadruple" tests, depending on how many substances are tested for.

• Ultrasound scan -  a nuchal translucency test checks the thickness of skin at the back of the baby’s neck (the nuchal fold) Thickening of this skin indicates a higher risk of Down's syndrome.

• Chorionic villus sampling- a  sample placenta tissue is taken and tested at 10-12 weeks.

• Amniocentesis – a sample of amniotic fluid (fluid surrounding the unborn baby) is taken at around 16 weeks

The chromosomes found in amniotic and chorionic villus samples give a definitive answer to whether the baby has Down's syndrome. However, amniocentesis is associated with a 1% chance of miscarriage and this risk is slightly higher with chorionic villus sampling. These tests are therefore only carried out after careful evaluation of the risks and benefits.Some women may decide to terminate the pregnancy if their baby has Down's syndrome. This can be a distressing decision to make. The Health Care Professionalscan provide support and reassurance during this time.

How Will My Baby Be Confirmed As A Down’s Baby?

Down’s Babies are usually diagnosed in the first few days after birth. Doctors and midwifes are trained to identify the physical characteristics associated with the condition. These include floppy limbs, low birth weight and a flat face and nose. Some babies display almost no physical signs while others may show all of them. A blood test is usually offered to help confirm the diagnosis.

More information about pregnancy checks can be found in our article Checks, Scans and Tests