Can Prenatal Screening Detect Down Syndrome in Babies?

In India, 23,000 to 29,000 babies are born annually with Down Syndrome, according to a study published in the Indian Journal of Paediatrics. This is a difficult condition to live with, not just for the child, but for the parents too. Prenatal down syndrome screening can help identify whether the baby is likely to suffer from the ailment. However, these tests can only offer a probability, after which the mother-to-be is usually advised specific diagnostic tests for further confirmation.

How Does the Prenatal Screening Work

With no risk of miscarriage, here’s what to expect from prenatal screening:

Genetic Screening

If you or your partner havea family history of genetic disorders, genetic screening might be advised by your doctor during pregnancy. Also, in case you have previously had a baby with a birth disorder, a genetic screening or a down syndrome test is a must for the second child.

First Trimester Screening

This test is done to identify certain genetic disorders, including Down Syndrome, in the foetus. This includes:

  • Maternal Blood Test: This test measures the presence of two substances in the mother’s blood, a hormone called human chorionic gonadotropin and a plasma protein A, associated with pregnancy. Abnormal levels of these two substances indicates a defect in the foetus. 
  • Nuchal Translucency Test: This test is carried out to test the nape of the foetus to check the collection or thickening of fluids in the neck tissues. In case of a defect, more fluid than the usual accumulates in the area. 
  • Nasal Bone Determination Test: Between 11 to 13weeks of gestation, an ultrasound is performed to check if the nasal bone is visible in the fetus. If not, the fetus might have certain chromosomal abnormalities. 

Integrated Screening

Thisdown syndrome scanis done during the first two trimesters to check for any abnormalities in the baby. In the second trimester screening, the levels of the following substances are measured:

  • Alpha Fetoprotein: This is a protein produced by the liver of the foetusand is present in the amniotic fluid. Abnormal levels of this protein might indicate various defects, includingdown syndrome, spina bifida and so on. 
  • Inhibin A: This is produced by the placenta and high amounts of inhibin indicate that the baby might have down syndrome. 
  • Estriol: The health of the foetus is determined by the level of this hormone produced by the placenta. 
  • Human Chorionic Gonadotropin: The level of this hormone can be tested after 11 days of pregnancy. Low or high levels of this hormone can indicate a number of defects. Since the level of this hormone doubles every 72 hours, the doctors must keep a check on the changes.

In case the down syndrome test is positive, it is important to remember that children with this condition will need extra love and support from you. There are multiple support systems, including special education programs, available to ensure good quality of life. If you have any questions, don’t hesitate to discuss it with your doctor.

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