Prenatal Genetics and Risk Assessment
About risk assessment and genetic counseling services
Whether you're pregnant or planning to get pregnant, Main Line Health is committed to helping you feel confident about making family planning decisions. Even without a known family history of a genetic condition, pregnancies still face risks. From one or both parents carrying recessive genes for certain conditions to the presence of ultrasound abnormalities, your genetic counselor can help to educate and advise you.
At several convenient locations, Main Line Health provides information about the most appropriate screening and testing options available before and/or during pregnancy based on your personal and family history.
Should you consider prenatal genetic evaluation?
Consider prenatal genetic counseling to learn about:
- Genetic testing options before pregnancy
- Genetic screening to identify whether there is an increased chance to have a child with a genetic disease
- Risks if the biological mother is 35 or older OR if the biological father is 40 or older
- Amniocentesis or chorionic villus sampling (CVS)
- Abnormal prenatal or carrier screening test results, amnio/CVS results or ultrasound result
- History of:
- Chemical or medicine exposure during pregnancy
- Multiple miscarriages (three or more)
- Genetic disease or birth defects in any blood relative
- Both parents being blood relatives of each other
Most health insurance plans cover the cost of genetic counseling and testing. Check with your insurance plan to find out what is covered.
Types of prenatal genetic risk assessment
You can undergo some genetic tests before getting pregnant to learn about genetic variations you could have and potentially pass down to children. Other tests to learn more about the health of the developing fetus happen during pregnancy. These tests include:
Carrier screening
One type of testing that can occur prior to or during pregnancy is called carrier screening. Carrier screening can inform a couple if they are at risk for having a child with recessive genetic conditions based on their own genetic profile. Carrier screening allows couples to consider their range of reproductive options with regard to pregnancy planning and testing. Approximately 80% of individuals may be carriers for recessive genetic conditions but have no family history of that condition. While a positive test is conclusive, a negative carrier screen result is more limited
Fetal testing
Fetal testing happens during pregnancy and falls into two major categories: screening tests (which determine the likelihood your pregnancy can be affected by genetic factors) and diagnostic tests (which can confirm or rule out a particular condition). Screening tests can provide information about the likelihood for specific genetic conditions, while diagnostic tests can provide more definitive information. Prenatal screening and diagnostic testing may provide parents with options regarding pregnancy and family planning. During pregnancy, parents can choose to have screening tests, diagnostic tests, a combination of both or no testing.
Sequential screening
Sequential screening can give parents information about the potential for certain chromosomal conditions or other birth defects such as open neural tube defects. This test is performed on blood samples taken from the mother in the first and second trimesters, along with a first-trimester ultrasound performed on the fetus to measure the "nuchal translucency" (NT) at the back of the neck.
Non-invasive prenatal screening (NIPS)
NIPS, also called cell-free DNA testing, is done any time after the ninth week of pregnancy. Performed on a blood sample from the mother, NIPS assesses DNA that is originally from the placenta to estimate the chance for certain chromosomal and genetic conditions. NIPS routinely screens for Down syndrome, Trisomy 18, Trisomy 13 and differences in sex chromosome number. Additionally, NIPS may be considered if the father of the pregnancy is age 40 or older, if there are specific findings on prenatal ultrasound or if there is a family history of chromosome microdeletions or duplications.
Chorionic villus sampling
Chorionic villus sampling (CVS) is a diagnostic test performed between 11 and 13 weeks of pregnancy. It involves taking a biopsy of the cells from the placenta, called chorionic villi. Cells are collected using a small, thin catheter that is placed through the cervix or a needle placed through the mother's abdomen.
Amniocentesis
Amniocentesis is a diagnostic test performed at 16 weeks or later during pregnancy. This technique involves collecting a sample of the baby's cells from the amniotic fluid using a needle that is placed through the mother's abdomen.
Our genetic counselors will analyze all of this information and help you determine which genetic tests, if any, might be appropriate. To learn more about genetics services, call 484.565.GENE (4363).