September 9, 2022

Considering the Patient Experience in Noninvasive Prenatal Screening

SWHR spoke with Patrick Wilson, MMSc, MS, CGC, Clinical Assistant Professor at the University of Oklahoma College of Medicine and Director-at-Large for the National Society of Genetic Counselors (NSGC), and Altovise Ewing, PhD, LCGC, a global health equity scientist, genetic counselor, and Director-at-Large for the NSGC about genetic screening. The following blog post captures takeaways from the conversation.

Prenatal genetic screening can be a helpful tool for future parents to make informed decisions about planning their family, pregnancy management, and future child-rearing. However, exploring the risk of passing on certain genetic conditions to your children can have emotional, social, and financial implications, so it’s crucial to understand what genetic screening is—and what it isn’t—and its role in your family’s broader prenatal and postnatal journey.

Noninvasive Prenatal Screening: Opportunities and Limitations

Among the types of genetic screening is noninvasive prenatal screening (NIPS), which is used to assess the risk of chromosomal aneuploidy—when there are extra or missing chromosomes in fetal DNA. The most common conditions screened with NIPS include Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13).

According to genetic counselor Patrick Wilson, MMSc, MS, CGC, obstetricians (OBs) should ideally present information about genetic screening to the patient at the first OB visit. At that time, the provider shares the various screening options with their patients, helps them decide if genetic screening is right for them, and, if so, which tests are most appropriate to include on the panel. Genetic screening is typically done at least 9 or 10 weeks into the pregnancy, and it can be included with other routine pregnancy blood work. Of note for families considering genetic screening, Wilson underscored that “declining [screening] at one point does not necessarily mean it cannot be done at a later point.”

The general sensitivity and specificity of NIPS is about 98-99% for correctly predicting risk of a chromosomal abnormality. However, the accuracy of NIPS is affected by a number of factors, particularly age. For example, Wilson said, in a 25-year-old mother, the screen has a lower positive predictive value than in a 45-year-old mother. He also noted that individuals with a higher body mass index (BMI) contain more body fluid and fat cells that could dilute the fetal DNA in the blood sample, resulting in the need to sometimes re-test to obtain a valid result. Genetic screening is not recommended for triplets or more because the test cannot distinguish between the babies.

Altovise Ewing, PhD, LCGC, a global health equity scientist, added that genetic tests “are only as great as the information or data that goes into the blueprint to create the tests.” Because genetics research has not historically explored genetic contributions of disease equally among various groups, some genetic tests are more comprehensive and specific for certain populations relative to other genetic tests. As a result, individuals from those underrepresented populations are significantly more likely to receive inconclusive and uninformative genetic screening results.

Choosing Whether to Undergo Genetic Screening

While any patient has the option to undergo genetic screening, not all of them do. Wilson says some of the reasons women may choose not to undergo genetic screening include not wanting to put additional stress on the pregnancy, having positive screening results in the past, or recognizing that the testing wouldn’t change the course of the pregnancy—in which case health care providers could monitor the baby with additional ultrasounds during pregnancy and then conduct diagnostic testing after delivery. Wilson recognized that, while for some, genetic screening is sometimes associated with termination of pregnancy, he emphasized that the testing is primarily for the management of the pregnancy and the baby’s health during and afterward:

“We do the screening to get a better understanding of the baby’s health, to better manage the pregnancy, and to ensure that—to the best of our ability—the baby is born in a healthy, or a healthier state, than it would have been had we not become aware of a possible concern for it… We do the screening to better manage the pregnancy and ensure that the baby is in the best state of health it can be in at the time of delivery.”

Navigating a Positive NIPS Result

For those who choose to undergo genetic screening and receive a positive result, the recommended next step is to be seen by a genetic counselor and/or a maternal-fetal specialist. A maternal-fetal medicine specialist (or perinatologist) is an obstetrician who has additional training in managing high-risk pregnancies where there can be health concerns in the baby and/or the mother. During that appointment, the provider will discuss the reason for the visit and what your test results could mean for the baby, perform an ultrasound to see if there are any features related to the potential health condition, answer any questions the family has, and offer diagnostic testing during or after the pregnancy to confirm the screening results. The conversation and path forward would all depend on what the mother and family are most comfortable with. When asked what piece of advice he would give to someone who has received a positive result on NIPS, Wilson reiterated that a positive result “does not actually mean that their baby is affected.” He said, “We need to do additional testing…to see how the baby is doing and whether it has any features related to that condition, and then move forward.”

If a physical abnormality is observed on the ultrasound, the family can meet with a pediatric subspecialist, who will follow the baby after birth. Forming this connection, Wilson said, will allow the family to learn more about their baby’s condition, have their questions answered sooner rather than later, and, hopefully, reduce some of the stress and anxiety that they may be experiencing.

Ultimately, genetic screening can serve several purposes, including:

Looking Ahead: Needs in Genetic Screening

While genetic screening remains a powerful tool, there is room for improvement, noted Ewing. To take full advantage of the full potential of genetic screening, she said, “It is imperative for the genomic medicine ecosystem to intentionally embed equitable and inclusive principles within genetics research.” Including diverse populations in genetic research will improve our ability to precisely understand the genetic underpinnings and implications of disease in all populations. “Genetics has gotten a bad name,” Wilson acknowledged, “but we are hopefully correcting that by showing that we do care about these babies. We do want them as a part of society… The more information we have, the better we can manage the pregnancy and the baby after it’s delivered.”

For more information about NIPS, view the following SWHR resources:

SWHR’s Noninvasive Prenatal Screening Program is supported by educational sponsorship from Illumina, Inc. SWHR maintains editorial control and independence over educational content.