Prenatal Testing

Will my baby be healthy? Thoughts about your baby's health are common and natural. To help answer questions concerning your baby's well-being, prenatal tests are available to help identify potential problems that could endanger you and your unborn child.

Routine prenatal tests are recommended by most physicians. Some tests are recommended for all women. Other tests are optional. Your doctor will explain the advantages and disadvantages of the optional tests. Some women refuse optional testing because of their religious beliefs or cultural traditions. Others take comfort in knowing as much as possible about their baby.

It is up to you to be informed and to understand how prenatal tests will impact you and your baby. Talk to your obstetrician. Understand what the tests measure, what happens during the test, and how you will handle the information obtained.

Increasingly, prenatal testing can detect conditions that are treatable and, in some cases, curable. Even when conditions cannot be treated, parents often gain valuable time to prepare emotionally and practically for the birth of a child with special needs. Diagnosis aids in planning the care required during the rest of pregnancy, delivery and for the baby's first days after birth.

Some prenatal tests only reveal the possibility of a problem. Many women who have positive results from screenings deliver healthy babies. Other tests are diagnostic and can detect abnormalities with a high degree of certainty.

Other tests are offered based on ethnic background. For example, patients with African American ancestry are tested for the sickle trait. Patients with Jewish ancestry are offered tests for a panel of genetic diseases more common in the Jewish population. Patients with Caucasian ancestry are offered testing to determine if they carry the gene for cystic fibrosis.

Screening for Down syndrome was previously only offered to women 35 and older and testing required an invasive procedure called amniocentesis. Now screening is offered to all pregnant women by means of blood testing at 16-20 weeks. Only those women with positive tests need to consider having an amniocentesis. The newest test, called the combined screening test can be performed between 11 and 13 weeks and involves an ultrasound to measure the thickness of the baby's neck skin (nuchal translucency) and assessment of two substances in a spot of maternal blood. Patients with positive results are offered chorionic villus sampling, a first trimester procedure.

All women with positive screening tests are referred to a genetic counselor for a discussion of test results and options for further testing. Consulting a genetic counselor is recommended for women considering first trimester combined screening or women who have a history of family genetic problems.

Most importantly, maintain open communication with your care provider throughout pregnancy. Ask questions. Stay informed!

Editorial provided by Linda Dunn, MD, chair, department of obstetrics and gynecology at Chestnut Hill Hospital in Philadelphia. Dr. Dunn is board-certified in maternal fetal medicine and clinical genetics as well as obstetrics and gynecology. She has special interest in genetic counseling, prenatal genetic testing and high-risk pregnancy.