Testing for three trisomies while in the womb

Persons with Down syndrome can live a meaningful and fulfilled life with adequate support from their family and the community. — Filepic

Moving into the 21st century, a great deal has been written about the advancement of women growing into leadership positions.

Everyday, female talents are breaking barrier after barrier, and the glass ceiling continues to move further and further up.

These progressive goals often include climbing corporate ladders, furthering their tertiary education, and reaching a level of financial stability to bear the steep cost of raising a child.

This shift in priorities has caused many women to delay marriage, resulting in a drop in birth rates and a rise in the age at which mothers give birth.

Unfortunately, this also means an increase in the chances of a mother birthing a child with chromosomal abnormalities – a risk that increases significantly after she reaches the age of 35.

The best known chromosomal abnormality is Down syndrome.

It is a condition in which a person is born with an extra set of chromosome 21.

Effects of Down syndrome might include varying degrees of mental retardation, hearing loss, ear infections and heart defects, some of which are present from birth.

Beyond Down syndrome (also known as trisomy 21), other common chromosomal conditions associated with older pregnant women are Edwards’ syndrome (trisomy 18) and Patau’s syndrome (trisomy 13).

Unfortunately, babies with trisomy 13 and 18 usually do not survive being born, and even if they do, the malformations of the child would be severe.

Test to prepare

To prepare for the possibility of raising a child who will require more care and attention than most, mothers should undergo non-invasive prenatal testing (NIPT).

The results of an ultrasound scan and the NIPT together will give a fairly accurate assessment of whether a fetus has either Down, Edwards’ or Patau’s syndrome. — AFP

This is a highly accurate prenatal screening that can be accomplished with a simple blood draw in order to check the fetus’ DNA.

This is possible as during pregnancy, DNA from the placenta breaks off and floats around in the mother’s bloodstream.

It is this placental DNA that will be analysed to determine the risk of the child being born with Down, Edwards’ or Patau’s syndrome.

While the placental DNA and fetal DNA are usually identical, there are times when they might differ.

Therefore, the accuracy of the test is not 100%, but close enough at 97% to 99% accurate.

Although the test can be done from nine weeks of pregnancy, it is better for a first-trimester detailed ultrasound scan of the fetus at 12 to 13 weeks of pregnancy to be done before the NIPT.

This is to enable the doctor to check for certain major structural defects that might be visible then.

If any suspicious signs like thickening of the skin at the back of the fetal neck are observed, then invasive testing like chorionic villus sampling should be carried out, rather than a blood test like the NIPT.

In the former, a needle – guided by ultrasound – is inserted into the placenta to withdraw a sample of the DNA there.

It is important to note that there are many varieties of fetal DNA tests offered by various labs.

Women should check with their doctor regarding the accuracy of each of these tests and the amount of fetal blood percentage that determines how accurate the test is.

Fetal blood percentage is the actual amount of placental DNA available in the mother’s blood sample.

It is also useful to remember that a low-risk fetal DNA report does not mean that the baby is structurally normal.

Babies can have various physical defects – like anencephaly, a condition in which the child is born without parts of the brain or skull; missing or deformed limbs; or a hole in the heart – but be genetically normal.

That is why a structural scan around 18 to 22 weeks of pregnancy is highly encouraged.

In addition, an NIPT test that reports low risk and a structural ultrasound scan that shows no abnormalities is also not a guarantee of a perfectly healthy child.

In other words, the baby may still develop learning issues or autism, which are not detectable via genetic tests or physical scans.

For this reason, it is best that parents are vigilant about the child’s development, and visit their paediatrician promptly should there be any concerns.

Ultimately, there is no method with current technology that can provide a 100% guaranteed answer if a child will be born with any birth defect or abnormalities.

But undergoing both NIPT and ultrasound scans should give reasonable surety as to the risk of a child having the three chromosomal conditions mentioned above.

Forewarned is forearmed

Tests like the NIPT and ultrasound scans basically serve as catalysts for parents to prepare themselves mentally and emotionally for their special child.

Expectant parents can equip themselves with the knowledge and mental preparation for taking care of a child with birth defects before the child is even born.

Through early detection, parents are able to educate themselves on what a child with special needs might require in terms of healthcare, education, social engagement and emotional support.

Beyond that, they will be able to seek out help from organisations that can provide information and support to parents of special needs children early on.

These include non-governmental organisations like Kiwanis for children with Down Syndrome, or the Cleft Lip & Palate Association Malaysia for babies with those structural defects.

Early knowledge also gives time to parents to come to terms with the fact that their child will be physically and/or mentally challenged.

Research has shown that the birth and care of such a child could increase parental stress levels tremendously, as well as potentially lead to rifts between them and other family members and/or friends.

Do seek help and information from other parents who have gone through the same experience, or read up on articles and check websites to get a better understanding of your child’s potential condition and needs.

All in all, caring for children with special needs is an endeavour that will undoubtedly challenge most families.

However, with the ongoing development of biotechnology and the health industry’s continued advancement, along with professional help being more accessible than ever, it is entirely possible for parents to ensure that their child will lead a meaningful and fulfilling life.

Dr Raman Subramaniam is a consultant obstetrician and gynaecologist. For more information, email [e-mail]. The information provided is for educational purposes only and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.