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How Is Down Syndrome Detected During Pregnancy?

Down syndrome is a genetic condition produced by an additional whole or partial copy of chromosome 21 due to faulty cell division. Down syndrome is characterised by developmental delays and physical characteristics caused by excess genetic material.

Individuals with Down syndrome have varying degrees of intellectual disability and developmental delays. It's the most frequent genetic chromosomal condition in children and the leading cause of learning impairments. Down syndrome affects one out of every 800 infants in the United States, with up to 6,000 children born with the condition each year. It is predicted that 85%of Down syndrome infants survive one year, with half of those living for more than 50 years.

We have also created a detailed information guide on Down Syndrome that you can check out on our website as Down Syndrome Information Guide.





What causes Down syndrome pregnancy?


All people with Down syndrome have an additional, essential part of chromosome 21 present in all or some of their cells, regardless of the form of Down syndrome they have. This extra genetic material disrupts the path of development, resulting in Down syndrome traits.


The additional complete or partial chromosome's cause is still unknown. The only factor that has been related to an increased risk of having a baby with Down syndrome due to nondisjunction or mosaicism is maternal age. A 35-year-old woman has a one-in-350 chance of having a child with Down syndrome, which jumps to one-in-100 by the age of 40. At the age of 45, the risk drops to about 1 in 30. The mother's age does not appear to be associated with the risk of translocation.


However, because younger women have greater birth rates, 80% of Down syndrome children are born to women under the age of 35. There is no conclusive scientific evidence that Down syndrome is caused by environmental factors or the behaviours of the parents prior to or during pregnancy. Down syndrome is caused by an extra partial or full copy of the 21st chromosome that can come from either the father or the mother. The father has been linked to approximately 5% of the occurrences.


What tests are done to detect Down syndrome?


A sample of genetic material is removed during Down syndrome diagnostic testing. After it is extracted, the sample is examined for additional chromosome 21 material, which could suggest a foetus with Down syndrome. The findings of the test are usually given to parents a week or two later. The processes for extracting samples are as follows.

  • Amniocentesis is a procedure in which a sample of amniotic fluid is taken and checked for the extra chromosome. This test is only available between weeks 14 and 18 of pregnancy.

  • CVS is a procedure in which a health care specialist removes a sample of cells from a section of the placenta, the organ that joins a woman and her foetus, and examines it for the extra chromosome. Between weeks 9 and 11, a pregnancy test is performed.

  • A health care worker collects a sample of foetal blood in the umbilical cord through the uterus using percutaneous umbilical blood sampling (PUBS). The additional chromosome is then detected in the blood. The most accurate diagnostic procedure is PUBS, which can validate CVS or amniocentesis results. PUBS, on the other hand, must be done later in the pregnancy, between the 18th and 22nd week.


Can you tell if a baby has Down syndrome in an ultrasound?

During pregnancy or after a child is born, health care practitioners can check for Down syndrome. For Down syndrome prenatal screening, a blood test and an ultrasound are performed during the first trimester of pregnancy. This is the most often used screening method in the first trimester. A blood test allows a doctor to look for "markers" in the mother's blood, such as specific proteins, that indicate an elevated risk of Down syndrome.

The health care professional then performs an ultrasound test, which creates images using high-frequency sound waves. Fluid near the back of a fetus's neck can be detected with an ultrasound, which can suggest Down syndrome. The measurement of nuchal translucency is the name of the ultrasound test. This combination strategy produces more effective or comparable detection rates during the first trimester than methods utilised during the second trimester.

Check our or blog on Treatments for Down Syndrome


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