Testing for Birth Defects
Fort Sanders Perinatal Center provides prenatal screening and diagnostic testing to evaluate the health of your baby and check for birth defects. While most babies are born healthy, a small number (1%) are born with major birth defects, and 3 to 4% are born with minor birth defects that may be caused by genetic, environmental or other factors.
There are ways to estimate risk for birth defects for families with or without chromosomal problems:
- Mother’s age. Women considered to be at an advanced maternal age, older than 35, are at an increased risk for chromosome problems.
- Family history
- Babies with chromosome problems can be born to younger women.
It is important to recognize the distinction between screening tests and diagnostic tests. Screening tests do not provide a yes or no answer, but do let a family know if the risk for a condition is higher or lower than expected. Diagnostic tests provide a yes or no answer.
Types of Birth Defects
The major categories of birth defects are chromosomal conditions, abnormalities involving a known mutation in a particular gene, structural birth defects unrelated to chromosomal conditions or a specific known gene, and birth defects due to certain maternal infections or environmental exposures.
Our genetic counselors will review your family history to help determine if your baby is at risk for a birth defect.
There are several ways to screen for chromosome defects. Screening tests are performed by ultrasound evaluation and maternal blood tests, either separately or in combination. The following screens are offered at Fort Sanders Perinatal Center:
- First trimester screening
- Maternal Serum AFP screening
- Sequential screening
- Quad screening
- Non-Invasive Prenatal Testing (NIPT)
Direct examination of chromosomes is required to determine the presence of a numeric chromosome defect, such as Down syndrome, trisomy 13 or trisomy 18. During pregnancy, DNA samples typically are collected through chorionic villus sampling (CVS) (typically done between 11 and 13 weeks) and amniocentesis (typically performed between 15 and 22 weeks).
Our genetic counselors are available to provide guidance about different screening and diagnostic testing options unique to your needs.
Regardless of age or calculation of risk, we offer the options of CVS or amniocentesis to all pregnant women who desire these tests. Depending upon your insurance plan, the testing may or may not be covered.