Posts Tagged ‘screening tests’

Today is World Down Syndrome Day

Wednesday, March 21st, 2018

What is Down syndrome?

Down syndrome is a chromosomal condition caused by extra genetic material. Typically, our cells contain 23 pairs of chromosomes. In the case of Down syndrome, a person has an extra full or partial copy of chromosome 21. This extra genetic material changes how the body and brain develop. People with Down syndrome have a few common physical traits, but each individual is unique and can lead a healthy active life.

We don’t know for sure why Down syndrome happens. Even though it’s a genetic condition, the majority of the cases are not passed on from the parents or family to the baby. Most cases happen because in the early stages of the baby’s development, there is a problem when the cells are dividing. However, there are some factors that may increase the risk of having a baby with Down syndrome, such as:

  • Mother’s age. The risk of Down syndrome increases with the mom’s age. Even though the risk is greater as your age increases, about 80 percent of babies with Down syndrome are born to women age 35 or less. This is because younger women have more babies than older women.
  • Having had a baby with Down syndrome. Up to age 40, for each pregnancy your chances of having another baby with Down syndrome is about 1 in 100 (1 percent). After age 40, the risk is based on your age. Talk to a genetic counselor to understand your risk of having another baby with Down syndrome.
  • Being a carrier of a genetic translocation. Both, men and women, can pass a genetic translocation to their baby. These cases are not very common. If you had a baby with Down syndrome before or if you or your partner have a family history of Down syndrome, it’s best to talk to a genetic counselor.

During pregnancy your health care provider will offer screening tests to see if your baby is more likely to have Down syndrome. These tests are offered to all pregnant women as part of regular prenatal care. However, a screening test won’t tell you for sure if your baby has Down syndrome. It only tells you if there is a higher risk. To know for sure you will need a diagnostic test.

How do you know if your baby has Down syndrome?

If you get an abnormal screening test result, your provider will recommend a diagnostic test. A diagnostic test will confirm if a baby has Down syndrome. There are few diagnostic tests:

  • Amniocentesis (also called amnio). This test checks the amniotic fluid surrounding your baby in the uterus to check for Down syndrome. You can get an amnio at 15 to 20 weeks of pregnancy.
  • Chorionic villus sampling (also called CVS). This test checks the tissue from the placenta to see if a baby has Down syndrome. You can get a CVS at 10 to 13 weeks of pregnancy.
  • Cordocentesis (also called percutaneous umbilical cord sampling or PUBS). For this test your provider inserts a thin needle into an umbilical cord vein to take a small sample of your baby’s blood to check for chromosome defects. You can get this test between 18 and 22 weeks of pregnancy. There’s a much greater risk of miscarriage with cordocentesis than with an amnio or a CVS. So you only get this test if other tests are unclear and your provider can’t confirm if your baby has Down syndrome any other way.

Down syndrome is also identified at birth by physical traits like: almond-shaped eyes that slant up, low muscle tone, a single line across the center of the palm of the hand, and a flattened face. But these traits won’t tell you for sure if your baby has Down syndrome, a chromosomal test call karyotype is needed to confirm this diagnosis.

Anencephaly: causes, risks & what you can do

Monday, January 25th, 2016

About 1,206 pregnancies are affected by anencephaly each year in the U.S.

Anencephaly is a serious birth defect in which a baby is born without parts of the brain, skull and scalp. As a baby’s neural tube develops and closes, it helps form the baby’s brain and skull, spinal cord, and back bones. Anencephaly is a type of neural tube defect (NTD) that happens if the upper part of the neural tube does not close all the way. A baby with anencephaly will be missing large parts of the brain that are necessary for thinking, hearing, vision, emotion and coordinating movement. Other parts of the brain are often not covered by bone or skin.

Babies born with anencephaly have reflexes such as breathing and response to touch and sound, however because of the severity of the condition, almost all babies with anencephaly die before birth or within a few hours or days after birth.

What causes anencephaly?

In most cases, the cause is unknown. Some cases are caused by a change in the baby’s genes or chromosomes. Anencephaly may also be caused by a combination of genes and other environmental factors. Scientists are continuing to study anencephaly in order to discover the causes.

What are the risk factors?

  • Low intake of folic acid before getting pregnant and in early pregnancy increases the risk of having a pregnancy affected by a NTD including anencephaly.
  • Babies born to Hispanic mothers are at an increased risk for anencephaly; reasons for the increased risk are not well understood.

How is anencephaly diagnosed?

  • During pregnancy: a woman can have screening tests done during her prenatal visits. Anencephaly would result in an abnormal result on a blood or serum screening test. Anencephaly might be seen during an ultrasound.
  • After a baby is born: anencephaly is immediately seen at birth.

Is there anything you can do to lower your risk?

Yes.

  • Take a multivitamin with at least 400 micrograms of folic acid every day before and early in pregnancy. Make sure to take your multivitamin even if you are not thinking about becoming pregnant any time soon. Since the U.S. started requiring that folic acid be added to certain foods, there has been a 28% reduction in cases of babies born with NTDs.
  • If you are pregnant, make sure you go to all of your prenatal visits and eat a well-balanced diet
  • Avoid alcohol and smoking and talk to your provider about any medications or drugs you are taking.

Have questions? Email us at AskUs@marchofdimes.org.