Genetic Testing Pregnancy

While all genetic tests can yield a treasure trove of information, none is as important or informative as pregnancy genetic testing.

Genetic testing is the analysis of your DNA and chromosomes, which can unlock the secrets of your genetic inheritance. It is used to find predispositions for diseases and conditions you may have inherited, as well as for other, non-medical purposes.

Pregnancy genetic testing is performed to discover what genetic conditions parents may pass on to the baby.

Genetic Conditions and Inheritance

Genetic testing during pregnancy can detect several conditions that can severely inhibit a child’s quality of life.

  • Birth Defects: This term is widely used to describe any physical anomaly seen at birth significant enough to be a problem. Many birth defects have no known cause. Spinal bifida, cleft palates and Tay Sachs disease are a few defects pregnancy genetic testing can reveal.
  • Down syndrome: This is a genetic disorder in which a child is born with extra genetic material, resulting in developmental delays and mental retardation. Down (or Downs) syndrome affects one in 800 babies, on average. The risk is less for pregnant women 34 and under and higher for women over the age of 34.
  • Neural Tube Defects: These detectable brain and spinal cord disorders are rare, present in less than 3 in 1000 births.

Pregnancy and Genetic Testing

Amniocentesis and Chorionic Villus Sampling (CVS) are common tools used in genetic testing for pregnancy.

An amniocentesis test is usually performed between 16 and 18 weeks into the pregnancy to test for genetic problems and determine the gender. A hollow needle is inserted into the abdomen to remove a small amount of amniotic fluid from around the fetus.

CVS testing is done earlier, between 10 and 12 weeks into the pregnancy. A small piece of the placenta is taken to check for genetic problems. Amniocentesis and CVS tests both carry slight risks of miscarriage.

Sonograms are a screening that virtually all pregnant women undergo. These are images created by the use of ultrasound so doctors can look at your developing baby. More in-depth sonograms, such as a nuchal scan, are done between 11 and 13 weeks in higher risk pregnancies to detect Down syndrome.

Genetic Testing for High-Risk Pregnancies

While most women have regular sonograms as part of their prenatal care, not all pregnancies are recommended for genetic testing. Age, family history and previous birth history will determine whether genetic testing for pregnancy is suggested. Women in the following circumstances should be tested.

  • If she is over 34 years old. Older women have a greater chance of having a child with a chromosomal defect. Though 35 is still rather young in the grand scheme of life, it is the age where pregnancies are considered at higher risk of genetic abnormalities. The odds of having a child with Down syndrome increase to one in 400 for women over 34.
  • If either the mother or father has a close relative with a genetically inherited illness. Even if the woman or her partner doesnt have the disease themselves, they may still be carriers.
  • If she has suffered multiple miscarriages. Two or more miscarriages may point to a genetic issue.
  • If the parents already have a child with a major birth defect.

While having a baby with a major birth defect is something every would-be parent thinks about at one time or another, it’s not something to dwell on. If you want to calculate odds, think just how determined your baby is to even make it to the womb.

Defects are the exception, not the norm. Advances in medicine and genetics take place every day. It is common for women to have healthy births not only in their thirties, but well into their forties — and some even in their fifties! The birth rate for women from age 40 to 44 years of age rose by 45 percent from 1995 to 2006.

The best way to increase your odds of having a healthy baby at any age is to take care of factors you can control. Avoid cigarette and cigar smoke, alcohol and any drugs not approved by your doctor. Add in rest, moderate exercise and regular prenatal care, and no matter what your age, you’ve greatly increased your odds of having a healthy child.

Resources

Baby Hopes (n.d.). Trying to conceive over 35: What are the risks of birth defects? Retrieved November 12, 2008, from the Baby Hopes Web site: http://www.babyhopes.com/articles/birthdefects.html.

Kids Health (n.d.). Genetic testing. Retrieved November 12, 2008, from the Kids Health Web site: http://kidshealth.org/parent/system/medical/genetics.html.

Pregnancy over 40 (2007). Birth defects: What you should know. Retrieved November 12, 2008, from the Pregnancy over 40-over 40 Motherhood Web site: http://pregnancyover40-over40motherhood.blogspot.com/2007/11/birth-defects-what-you-should-know.html.