There’s nothing like the poking and prodding that a pregnant woman undergoes on her way to delivery day, though it’s all in the name of good health, of course. The more information both doctors and patients gather, the more empowered both parties are to make sound healthcare decisions.
One of the more difficult choices pregnant women face is whether to undergo genetic testing, which has become more standard in recent years as modern science has evolved. Unlike tests that can reveal whether you’re having a boy or a girl, genetic tests look for markers of birth defects and disorders like Down syndrome and cystic fibrosis. The American College of Obstetricians and Gynecologists recommends offering the option of both screening and diagnostic tests to all pregnant women, especially to women of advanced maternal age (who are more prone to having babies with birth defects) or those who have a history of genetic disorders. So if you’re pregnant, your doctor will inevitably ask if you want to undergo testing.
Screening involves a simple blood test and an ultrasound during the first trimester or the early part of the second trimester. Diagnostic tests are more invasive and performed via amniocentesis or chorionic villus sampling (CVS), usually in the second trimester. The latter is usually done only when screening test results are worrisome, in order to capture a more accurate picture.
To many women, the options present a moral dilemma. Some mothers have such a firm resolve to carry their babies to term no matter what the test results might show that they opt out. But others want to know everything they can about their baby’s health and future, not just so they can determine whether they will continue their pregnancy, but also so they’re prepared for any special needs their child might have. Modern science allows even for the screening of embryos that were obtained via fertility treatments, giving parents the option to decide if they want to have those embryos implanted at all.
With all of this in mind, here’s a look at what parents and experts think about genetic testing, as well as what some of the research shows:
What the research says
There is significant evidence that widespread genetic testing curbs the number of inherited disorders. “We’re definitely seeing decreased rates of certain genetic disorders as a result of carrier screening,” Wendy Chung, MD, clinical genetics chief at Columbia University, told the Associated Press. Births of babies with cystic fibrosis, Tay-Sachs, and other diseases have dropped since testing came into wider use, according to an Associated Press review of studies and interviews with geneticists and other experts. Presumably that’s because many moms choose to terminate as a result of positive test results.
One of the deterrents of more invasive diagnostic testing is the chance of a negative side effect, including an increased risk of miscarriage. But for many moms, the benefit of knowing if their baby has a defect or disorder far outweighs that.
Fortunately, new research shows that a more accurate blood test, referred to as cell-free DNA prenatal screening, may eliminate the need for diagnostic testing in a significant number of pregnant women. A study published in The New England Journal of Medicine found that this simple blood test is more accurate than the standard methods to screen for chromosomal abnormalities, paving the way for a new generation of genetic tests that are far less invasive. This is the first U.S. study to compare the newer genetic tests with current screening tools in large numbers of low-risk pregnant women. It found that the new tests produced far fewer false-positive readings than their more invasive counterparts, such as amnio and CVS.
What the experts say
Some doctors recommend genetic tests more strongly in cases where ethnic background and family history increase the likelihood that a child will be born with an abnormality. “That’s because the diseases for which genetic testing is currently offered tend to be more common among certain ethnic groups,” Angela Trepanier, co-director of the genetic counseling program at Wayne State University and president of the National Society of Genetic Counselors, told Parents magazine.
Genetic testing can even be done before you start trying to get pregnant. “But because so many pregnancies are unplanned,” she says, “many couples get screened early in pregnancy.”
The cell-free DNA test will probably have a major effect on both doctors and patients as it becomes more prevalent. “Nine out of 10 women who are currently being referred for further testing would not need invasive tests,” said the lead author of the study, Diana Bianchi, MD, executive director of the Mother Infant Research Institute at Tufts Medical Center’s Floating Hospital for Children, to the New York Times. This means fewer women will be encouraged to have more invasive testing, resulting in fewer miscarriages.
What the parents say
“I did not have any genetic testing although my doctor suggested it due to my age because I wanted the child no matter what.” — Darlene Wilson Shue, Fort Worth, Texas.
“I did with my first because of my age, ancestry, and the infertility treatments I was given. This was not to terminate if we found something but to be prepared to give him whatever might be needed so he would have the best opportunity to thrive.” — Lynn Moretti Harper, South Kingston, R.I.
“I did when my lab results and ultrasound pointed to Trisomy 18, and I was glad I did. Knowing the decision that had to be made, I couldn’t live without knowing if he had Trisomy 18. I would definitely do it again. However, if I didn’t have any markers of concern, I would not.” — Jolene Wells Hanlon, Las Vegas.
”I chose not to have it with my four pregnancies for religious reasons. I never considered abortion an option, so I saw no point in doing any genetic testing.” — Julie Cash King, Lehi, Utah.
The bottom line
The decision whether to undergo genetic testing is a personal one that all mothers face, and no two pregnancies are the same. A 20-something first-time mother may decide to forgo genetic testing due to low risk, but change her mind with her second or even third pregnancy due to advanced age, a series of miscarriages, or other factors that increase the risk of birth abnormalities, such as a previously unknown family history.
The good news is that genetic testing is becoming less invasive, thereby reducing the odds of miscarriage and other side effects that often add to a mother’s concern.
Whatever decision you make, it’s important to consider what you might do if results came back positive or negative. Discuss the risks and implications with your partner, doctor, and anyone whose opinion you trust, but ultimately the decision to move forward with genetic testing is yours.
If you believe that knowing about any defects will significantly alter your course of action, whether that’s choosing to terminate or seizing the opportunity to learn about your baby’s condition and prepare to provide it with the best possible care, then genetic testing might be worth considering.