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Facts About Down Syndrome Pregnancies

Down syndrome is also known as Tristomy 21. Approximately 6,000 babies are born every year in the U.S. with Down syndrome, making it the most prevalent birth defect. Down syndrome most commonly occurs when an extra 21st chromosome develops in the egg or sperm prior to fertilization. When fertilization occurs, there are then three of these chromosomes instead of two. Then as the cells split and replicate, the extra chromosome is duplicated in every cell. The risk of Down syndrome increases significantly with maternal age. While, a 20-year-old has a 1 out of 1600 chance of having a baby with Down syndrome, a woman who is 45 has a 1 out of 30 chance of having a baby with Down syndrome. Down syndrome pregnancies do not present any different symptoms than any other pregnancy. Down syndrome can only be diagnosed by using a prenatal test or by examining the newborn baby.

  1. Ultrasound

    • During the first trimester, most OB/GYN's will conduct an ultrasound. During this routine test, the ultrasound technician will examine the skin behind the neck to see if it indicates the baby may have Down syndrome.

    Blood Tests

    • During the first trimester, the mother's blood will be checked for normal protein levels. Then during the second trimester, the mother's blood will be checked to determine if the fluids coming from the baby's brain, blood, spinal cord and amniotic sac are normal (quad marker screen). Also, a triple screen blood test may be used to check levels of alpha-fetoprotein and human chorionic gonadotropin.

    Amniocentesis

    • If the ultrasound examination or any of the blood tests described above appear to be abnormal, the doctor may recommend an amniocentesis. During this test, amniotic fluid will be extracted from the mother's womb and then be tested for Down syndrome markers.

    Chronic Villus Sampling

    • Another way to check for chromosomal problems is by analyzing a sample of tissue taken from the villa. The placenta is attacked to the uterus with the villa.

    Testing Accuracy

    • None of the tests mentioned here are absolutely perfect and results may be incorrect in some cases. A mother may be told that her baby is going to have Down syndrome when the baby actually does not have the disorder or a mother may be told that the tests are all alright when the baby actually has Down syndrome.

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