Genetics and Pregnancy

New Patient Appointment or 214-645-8300

UT Southwestern Medical Center’s preconception and prenatal genetics service connects patients with board-certified genetic counselors specializing in genetic testing and pregnancy. Our team helps patients understand information and make decisions about genetic testing that are right for their family.

Compassionate, Knowledgeable Genetic Counseling for Pregnancy Planning

Genetic counselors provide guidance to individuals and couples who are planning a pregnancy (preconception) or who are currently pregnant (prenatal). They discuss potential genetic risks that might impact pregnancy so patients can make informed decisions about genetic testing and understand their test results.

At UT Southwestern, we understand that every pregnancy and every family is unique. That’s why we offer personalized genetic counseling to help patients navigate concerns or questions they might have before or during pregnancy. Our genetic counselors work together with a patient’s obstetrician, maternal-fetal medicine specialist, reproductive endocrinologist, or other specialists to support patients and provide coordinated care.

Reasons for Preconception or Prenatal Genetic Counseling

Patients can be referred for preconception or prenatal genetic counseling for a variety of reasons, including:

Patient or partner has a family history of a genetic condition
Patient has had a previous pregnancy or child born with a genetic condition
Patient or partner is a carrier for a genetic condition
Patient or partner has a genetic condition that could be passed down to a child
Patient or couple would like screening for genetic conditions prior to becoming pregnant
Patient and partner are related by blood
Patient has a history of recurrent miscarriages
Patient is at an increased risk for specific age-related genetic conditions
Blood test during pregnancy has indicated an increased risk for Down syndrome or other genetic condition
Ultrasound during pregnancy has revealed concern for a difference in fetal development
Patient is considering having an amniocentesis or CVS (chorionic villus sampling) for any reason
Couple is pursuing in vitro fertilization (IVF) with genetic testing of embryos

Prenatal Diagnostic Testing

Genetic counseling involves a discussion about various screening and diagnostic genetic tests that are available to the patient.

Screening tests estimate risks for certain genetic disorders. They can be performed on a blood sample or sometimes using a saliva sample.

Prenatal diagnostic tests provide definitive genetic information about a pregnancy or fetus. To do so, they require a sample from the pregnancy. We offer two prenatal diagnostic tests at UT Southwestern: chorionic villus sampling (CVS) and amniocentesis. Both are performed by our maternal-fetal medicine physicians, who specialize in caring for high-risk pregnancies and performing procedures during pregnancy.

Chorionic Villus Sampling (CVS)

CVS is typically performed between 11-13 weeks gestation. We begin with an ultrasound of the uterus to locate the placenta and fetus. CVS involves collecting a tissue sample from the placenta, or a placental biopsy. There are two ways of obtaining the placental sample, depending on where the placenta is located inside the uterus.

In the abdominal method, a thin needle is inserted through the abdomen to reach the placenta.
In the cervical method, a small catheter is inserted through the cervix to reach the placenta.

Once the sample is obtained, it is sent to a genetic testing laboratory. Cells from the sample can be used to test the chromosomes or genes of the pregnancy.

Amniocentesis

Amniocentesis can be performed any time after 16 weeks gestation. We begin with an ultrasound of the uterus to locate the placenta, fetus, and the surrounding amniotic fluid. A pocket of fluid is identified on the ultrasound. A thin needle is then inserted through the abdomen into the uterus to withdraw some amniotic fluid from that pocket.

The fluid is sent to a genetic testing laboratory. Cells from the fluid can be used to test the chromosomes or genes of the fetus. The fluid can also be used to test for other substances such as infections or indicators for spina bifida in the fetus. The amniocentesis procedure only takes a couple minutes.

Both prenatal diagnostic tests are associated with a very small risk for complications or miscarriage. The risk is less than 1%, or in between 1 in 500 to 1 in 1,000. We take precautions with every prenatal diagnostic procedure to avoid complications, both during and after. For example, all patients who have a CVS or amniocentesis are recommended to limit activity for the rest of the day.

The results from a CVS or amniocentesis test can take between three days to four weeks or longer, depending on the tests being performed at the genetic testing lab. A genetic counselor will discuss all testing options with patients, and results are shared as soon as they are available.

Preconception and Prenatal Genetic Counseling: What to Expect

Preparing for the Visit

Genetic counseling sessions include a detailed pregnancy history and family history assessment. It can be useful to clarify family health history information prior to genetic counseling, particularly if there is concern about a specific condition in the family.

The genetic counselor asks questions about the health of the patient or couple as well as their children, siblings, parents, aunts, uncles, and cousins. Questions that a genetic counselor might ask about family health history include:

Is there anyone in the family who was born with a known genetic condition, birth defect, or intellectual disability?
For the individual(s) in the family with a known genetic condition, was genetic testing performed? Is a test report available?
Is there anyone in the family who has had three or more miscarriages?
Are there any babies or adults in the family who passed away suddenly with no known cause?
Are you and your partner’s families related by blood?

In addition to discussing the family history, it’s helpful for the genetic counselor to have copies of any previous genetic testing results for the patient or pregnancy. These may have been sent with the genetic counseling referral, or they can be brought in by the patient.

During the Visit

During a genetic counseling session, patients meet with one of our genetic counselors either virtually or in person. Sessions typically last 30 to 45 minutes. The visits include:

Reviewing a detailed pregnancy history and family history
Discussing genetic test results or ultrasound findings
Assessing the risk for inherited or sporadic genetic conditions based on personal or family history, age, or previous test results
Discussing options for additional genetic testing
Coordinating any testing desired by the patient or couple

Patients have the opportunity to ask questions during the visit and to remain in contact with their genetic counselor afterward.

Genetic tests for the patient or partner are typically done via blood or saliva. Some genetic tests for a pregnancy can be done via maternal blood or ultrasound. Others require procedures to obtain a sample of amniotic fluid (amniocentesis) or biopsy of the placenta (chorionic villus sampling) for genetic testing of the pregnancy.

Test results are provided over the phone by the genetic counselor and are available in a patient’s UT Southwestern MyChart account.