Getting Testy: The Pros and Cons of Prenatal Genetic Testing on Baby On The Way - Winnipeg - Baby Products, Baby Clothing, Baby Resources, Pregnancy Forums, Baby, Babies, Newborns, Expecting Resources

It’s not the sunniest of topics, but every expectant couple will have to discuss it at some point during their pregnancy: the question of prenatal genetic testing. We’d all like to hope for the best and dream of bringing home a healthy baby, but the sad fact is that some babies are born with health problems, ranging from mild to severe.

Prenatal testing is a way to find out in advance whether your child has a congenital problem. Tests are performed by analyzing small samples of blood or body tissue, such as amniotic fluid, and can often pinpoint missing or defective genes, and detect a variety of genetic diseases and disorders.

Screening tests are used to identify pregnant women who have a greater chance of giving birth to a baby with serious birth defects. They do not determine whether there is a problem, but rather that there could be a problem.

Diagnostic testing is used to determine whether a baby is affected by a particular problem. However, they have their limitations. For one, there is no single diagnostic test that can screen for every possible problem. Some problems simply cannot be detected until after birth. Also, a diagnostic test cannot accurately determine to what degree a baby is affected by an abnormality. For example, when a problem gene on chromosome number 7 is identified, doctors cannot predict whether the child will have mild respiratory symptoms, or severe lung problems associated with cystic fibrosis.

Still, prenatal testing can be an invaluable tool, especially if it should reveal that your baby has a problem. Learning this in advance can allow you to make special arrangements, such as scheduling a Caesarean or preparing to give birth in a state-of-the-art neonatal facility. Depending on the nature of the problem, doctors may also be able to administer medical treatment to the baby in utero. Lastly, if your baby’s problem is life threatening, it may enable you to make the difficult decision to terminate the pregnancy.

Ultimately, this is a decision that you and your partner should make together, and you should never let your caregiver pressure you into submitting to genetic testing if you don’t feel comfortable with it. Many couples have concerns (with good reason) about the accuracy of certain types of testing and feel that this uncertainty only adds stress and anxiety to their pregnancy.

Maternal serum screening is generally performed between the 16th and 20th week of pregnancy. A blood sample is taken from the pregnant woman and analyzed. The results are plugged into a formula, which predicts the woman’s odds of giving birth to a baby with certain types of birth defects. The main problem with this type of screening test is the number of women who receive a false positive (19 out of 20!). This can be a major source of stress when it turns out that nothing is wrong. However, it can also lead to more testing which may reveal that there is indeed a problem.

Some expectant women are at risk of having a baby with a chromosomal disorder such as Down syndrome. In these cases, a nuchal translucency measurement test can be given in weeks 10 to 14 of pregnancy to help estimate the risk of Down syndrome. This test uses ultrasound to measure the amount of fluid that has accumulated at the back of the fetus’ neck, between the skin and the underlying structures. When a fetus has a chromosomal disorder, the amount of fluid at the back of the fetus’ neck tends to be increased. If this screening test shows a high risk of Down syndrome, it can be followed by a diagnostic test such as chorionic villus sampling within the first three months of pregnancy, ideally at 10 to 12 weeks gestation, or amniocentesis after week 16.

An ultrasound may be used throughout pregnancy as both a screening and diagnostic tool. An ultrasound can detect a heartbeat, the presence of twins or multiples, and can monitor the growth and development of your baby. The most accurate time to date a pregnancy is during the first trimester. However, the most accurate time to screen for fetal anomalies is at 18 to 20 weeks.

Amniocentesis is a test typically performed between weeks 16 and 18 week of pregnancy. A fine needle is inserted into the woman's abdomen to remove a small amount (less than an ounce) of amniotic fluid from around the developing fetus. This fluid can be tested to check for problems, such as chromosomal defects, neural tube defects, genetic and skeletal diseases, fetal infections, central nervous system diseases, blood diseases, and chemical deficiencies. It can also be used to determine the sex of the child. When there's risk of cesarean section or premature birth, amniocentesis may also be done to see how far the child's lungs have matured. Amniocentesis carries a slight risk of inducing a miscarriage or premature labour.

Chorionic villus sampling (CVS) is usually performed between 10 and 23 weeks’ gestation by passing a catheter through the cervix, or inserting a needle through the abdomen to remove a small piece of chorionic villus tissue (which will eventually become the placenta). The tissue is examined and can detect problems, such as Downs syndrome, sickle-cell disease, thalassemia, cystic fibrosis, hemophilia, Huntington’s disease, and muscular dystrophy. Chorionic villus sampling is an invasive test, and carries a risk of miscarriage, at a rate of 1%.

Some couples may wish to skip genetic testing altogether. They feel they don’t need the added fear, stress, and anxiety in their lives, and want to blissfully enjoy their pregnancy and let nature take its course. Others may wish to arm themselves with as much information as possible, and to prepare for any eventuality. It’s a matter of choice for all couples, and not a question of right or wrong, despite what others may have to say about it. Be sure to discuss prenatal testing with your doctor, and clarify any questions and concerns you may have.