Prenatal Genetic Counseling
Genetic tests performed during pregnancy can show your chances of having a child with a disease or some other problem carried in your genes. All women are offered the following tests during pregnancy, but whether you choose to have the test done is a personal choice. To schedule an appointment with a genetic counselor, ask your doctor or nurse midwife for a referral to Genetic Counseling.
- Amniocentesis: Baby's chromosomes can be studied in samples of amniotic fluid. When needed, this is typically done between 15 and 18 weeks. You will have complete genetic counseling before amniocentesis. Not all pregnant women need this test.
- Cell-free DNA Screening: This blood test is an advanced screening tool for chromosome conditions that is more accurate than other screening options. Some insurance companies will not cover the cell free DNA test unless there is a high risk for a chromosome abnormality. This test can be done starting at the 10th week of pregnancy. It can identify Down syndrome, trisomy 13, and trisomy 18, as well as abnormalities with the sex chromosomes. If a higher risk is identified, a diagnostic test can be performed to confirm or rule out a chromosome condition. There is no risk to the pregnancy with this test.
- Chorionic Villus Sampling: This test is also used to study baby chromosomes before birth. Tiny amounts of placenta are removed between weeks 9 and 13. If you need this test, you will be referred to a center that does this procedure.
- Cystic Fibrosis Carrier Testing: You can choose to be tested to see if your baby has an increased chance of having cystic fibrosis (CF).
- Expanded Carrier Screening: This test determines whether the mother and/or father is a carrier of any recessive gene mutations. Recessive means that a mutation must be present on both versions of a gene (one inherited from the mother and one from the father) for a child to have the disorder. Being a carrier means that one version of a gene has a mutation and the other version does not. Carriers are usually healthy and unaware that they are carriers. If both parents are carriers of a recessive condition, then each pregnancy has a 1 in 4 chance of being affected by the condition. This testing typically starts by drawing blood on the mother, then testing the father only if the mother is found to be a carrier.
- Family History Risk Assessment: Questions are asked about health history of immediate family and extended relatives to find if a family history of health problems might increase a baby's chances of being affected by a genetic condition or birth defect.
- First Trimester Screening: This screening tells you your chances of having a baby with Down syndrome, Trisomy 18 or Trisomy 13 using information from an ultrasound measurement and a blood sample taken from a finger poke. The blood test needs to be done between 9 weeks gestation and 13 weeks 6 days gestation. The ultrasound is a measurement of an area on the back of the baby's neck. It is done between 11 weeks gestation and 13 weeks 6 days gestation. This is the most commonly performed screening process for Down syndrome, Trisomy 18 and Trisomy 13.
- Maternal Serum Screening: Sometime during your fourth month, you can choose to have Maternal Serum Screening performed. This blood test can tell you if there is an increased chance your baby may have Down syndrome or spina bifida. This test does not need to be done if you have had the first trimester screen.
- Ultrasound: Using ultrasound to make an image of the baby, placenta and uterus has become widespread. At Gundersen, we perform this service in Obstetrics. A routine ultrasound is done at about 20 weeks to provide a detailed examination of your baby to evaluate for the presence of birth defects. Not all birth defects are detected by ultrasound. Ultrasounds may also be done earlier in your pregnancy to confirm dating or with some screening tests.
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