What You Need to Know About Prenatal Testing for Down Syndrome and Other Genetic Conditions
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A mother’s worry for her child’s health and well-being begins much before they’re even born and prenatal testing plays an important role in easing this anxiety of future parents. These tests help detect any congenital (from birth) problems that could lead to birth defects or genetic diseases. Having all the information beforehand helps plan appropriate treatments for before and after the baby is born. For pregnant women, these not only help ensure a healthy and smooth pregnancy, labour and delivery but also help avoid any adverse post-pregnancy events.
A recent study published in the European Journal of Human Genetics, conducted by researchers from Massachusetts General Hospital (MGH) found that the number of babies born with Down Syndrome (DS) has reduced to almost half with the increase in prenatal testing. In 2016, the same team recorded a 33% decrease in babies born with DS in the United States.
DS is a congenital disease that occurs due to a defect in chromosomes and leads to some physical and intellectual abnormalities. The new noninvasive prenatal screenings (NIPS) help to detect such chromosomal abnormalities by the ninth week of pregnancy. This facilitates the expecting couples as well as doctors to take further prenatal actions. Brian Skotko, a medical geneticist at MGH and the senior author of the aforementioned article said, "Countries that are grappling with funding decisions for NIPS should certainly be having deep discussions about its impact on the country's Down syndrome population.” The study emphasises on the importance of prenatal screening and its impact on the DS prevalence in different countries where the study took place.
DS is considered one of the most common congenital diseases worldwide and India is one of the countries with the highest number of babies born with DS every year. Further discussions on prenatal screening would not only help in decreasing DS cases but also help detect other congenital or hereditary diseases early in the pregnancy. For example, detecting neural tube defects like spina bifida (where the spine doesn't form properly and can lead to abnormal growth and deformity throughout a child's life) can help parents and doctors figure out if surgical procedures can correct the problem.
During your pregnancy, your doctor may recommend getting many different tests, some of which may include the following:
1. Blood test (sequential integrated and serum integrated screening)
Blood tests are done during the early days of pregnancy. They help find if the mother has any infections such as HIV, hepatitis-B, syphilis or other conditions such as anaemia that could infect or disrupt the normal development of the baby. It also helps determine the Rh (factor that determines +ve or -ve blood group) incompatibility within the mother and the baby. This happens if the mother is Rh-negative and the foetus is Rh-positive.
2. Ultrasound tests
Ultrasound imaging during the first trimester helps to determine the proper growth and development of the baby. It also shows if there is any flaw in the development of the organs and bones. A special ultrasound test, known as the nuchal translucency ultrasound, performed between the eleventh and fourteenth week of pregnancy, can help diagnose DS in the growing baby.
1. Ultrasound test
An ultrasound test helps evaluate any anatomical changes from head to toe in an effort to help diagnose any major development issues.
2. Blood glucose screening
Some pregnant women get gestational diabetes (diabetes that occurs during pregnancy), which may cause problems during labour. A glucose screening test checks for blood glucose levels in pregnant women and helps plan the delivery of the baby. Women with gestational pregnancy may need a cesarean delivery.
3. Amniotic fluid testing
In amniocentesis, the amniotic fluid is tested to find any genetic abnormalities such as DS and spina bifida. This test is done after week 15 of the pregnancy.
1. Streptococcal infection screen test
This test helps detect any Group B streptococcal infections that pose a serious risk of infection in the newborn and mother.
For more information, read our article on Checkup during pregnancy.
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