The Hope and Heartache of Prenatal Screening

“God gives you what you’re supposed to have.”

With these words Marcie Smith, sitting in her obstetrician’s office with new life blooming in her womb, urged the genetics counselor to respect her decision against prenatal screening. At 45 years old, Smith knew she was at high risk for carrying a baby with Down syndrome. She understood the statistics. But she had already experienced a false-positive screen in a prior pregnancy, and didn’t want to revisit the stress of another inaccurate result. God created this little human, she thought. If he really wants this baby to be in this world, he’ll allow that to happen.

Her assurance did not convince her clinicians. After listing the plethora of chromosomal abnormalities that could afflict the baby, Smith’s obstetrician suggested an abortion. The genetics counselor abandoned all tact, and accused her of being “irresponsible” for carrying her pregnancy to term without genetic screening. Smith, buoyed by her faith in God’s sovereign goodness, remained resolute. But she left the appointment in tears, her initial joy at the unexpected pregnancy giving way to anguish.

Why Doctors Screen

No one should ever endure the bullying that Smith suffered in her doctor’s office. Yet even in the most sensitive of physician encounters, many women experience similar anxiety regarding questions of prenatal genetic screening. The American College of Obstetrics and Gynecology (ACOG) recommends that obstetricians offer all women these tests early in pregnancy, but conversations about their risks and benefits vary. While at first glance screening seems helpful, without compassionate and in-depth counseling these tests can aggrieve women still rejoicing over the news of a baby.

Prenatal screening aims to detect possible Down, Edwards, and Patau syndrome (trisomies 21, 18, and 13, respectively) in a developing baby and may also evaluate for neural tube defects like spina bifida. Traditional assays measure traces of biomarkers in the bloodstream, although over the past few years evaluation of placental “cell free DNA” has also gained popularity for its potentially improved sensitivity. Importantly, these screening tests are not diagnostic. False positive and negative results do occur, and any positive screen requires confirmation with an invasive test like amniocentesis or chorionic villous sampling.

The aim of prenatal screening is to help families prepare, both practically and emotionally, for terminal illness or disability in an unborn baby. The abnormalities in trisomy 13 and 18 are so severe and pervasive that most of these children die in utero. Of those babies who survive to delivery, most succumb to their birth defects within one year, although studies show that up to 13 percent who undergo aggressive treatment may live until age 10. Prognosis for Down syndrome is much better, with a median life expectancy of about 60 years; the threats of miscarriage and stillbirth still loom, however, affecting up to 30 percent of Down syndrome babies after amniocentesis.

We must never knowingly end the life of a child created by and for God, no matter how merciful our intent.

In many cases, the threat of a genetic disorder prompts families to end a pregnancy. One systematic review suggests that between 1995 and 2011, 67 percent of Down syndrome babies were aborted after diagnosis. For Christians, this approach is out of the question. Fearfully and wonderfully made by God, we are his image-bearers (Gen. 1:26), known and cherished by him even before we emerge from the womb and greet the glare of hospital lights (Ps. 139:13–16). We must never knowingly end the life of a child created by and for God, no matter how merciful our intent (Ex. 20:13). For believers, then, prenatal screening only offers time to ready the heart for possible pregnancy loss, and to plan for the rigorous challenges of caring for a disabled child. In small rural hospitals or resource-poor settings, early detection of a genetic abnormality can facilitate transfer of care to a hospital better equipped to manage potential severe illness in a baby. It enables families to gather their resources and seek out support ahead of time, and to prayerfully consider the road ahead. And to grieve. And if appropriate, to research palliative care options for their baby.

Potential for Error

Yet even these benefits come with an important caveat. Prenatal screening tests have variable accuracy, with false positives—results suggesting defects in a baby who is actually healthy—occurring in as many as 10 percent of cases. Given this low specificity, the ACOG emphasizes that families should never make decisions on the basis of prenatal screening alone. Instead, they recommend that women with a positive screen undergo confirmatory studies. But even these secondary tests, though more accurate, are still prone to error, and confer risks of injury and fetal loss.

Observations of these error margins persuaded Erin Wallace, a nurse and mother of four, to forego prenatal screening in her own pregnancies. She remained open to the concept until nursing school, when she witnessed the emotional turmoil of a couple who delivered a baby with Down syndrome despite a negative amniocentesis. “To see this family go to the level of an amniocentesis, which carries risks, and to still go through the stress of a false result, had a huge impression on me,” she recounts. “Abortion was not an option, and so I knew the results wouldn’t have made a difference in my pregnancies, except maybe to make me anxious. And God says we should be anxious for nothing.”

The lesson from such anecdotes is that prenatal screening tests are a choice, not a mandate, and should be pursued only after a careful weighing of their implications. The ACOG emphasizes that “the choice of whether to perform screening or diagnostic testing for aneuploidy depends on the women’s goals and values and her desire for informational accuracy,” and that “after counseling, patients may decline screening or diagnostic testing for any reason” (emphasis mine). These tests are not vital to care for the baby, as a 20-week ultrasound will usually reveal any dangerous anatomic defects. So prenatal screening tests are merely an option, an opportunity to prepare for challenges that lie ahead. Even then, however, screening only helps when viewed realistically, with sober recognition of its potential for error.

Question to Ask

For Marcie Smith, the choice was clear. “Even if he had these chromosomal abnormalities they threw at me, it would not have mattered,” she recalls, thinking about the anguish she suffered over her son, who ultimately was born healthy. “Not everyone is built the same. We’re meant to love people with disabilities. It teaches us to have more kindness and patience and joy.”

Perhaps, then, the most important question to ask when weighing the benefits of prenatal testing is whether or not the screening will help us to better nurture the little ones God entrusts to our care, which is a calling as unique and individualized as God’s pairing between mother and child.

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