How Much Genetic Information From Prenatal Testing Do Pregnant Women Want?

“Pregnancy 1” by operalynn is licensed under CC BY Interview with:
Professor Jane Halliday, PhD
Group Leader, Public Health Genetics
Murdoch Childrens Research Institute
The Royal Children’s Hospital
Parkville, Victoria  AUS What is the background for this study?

Response: The aim of the study was to examine the choice that pregnant women make about the amount of genetic information they want from their pregnancy. Women who underwent prenatal testing via chorionic villus sampling (CVS) or amniocentesis were recruited from across seven sites in Victoria.

Provision of this choice is not routinely offered but we thought it was important to look at this issue carefully, in a real-time setting, because, over the last five years, advances in technology have transformed how genetic abnormalities can be detected during a pregnancy.  Rather than examining genetic material (chromosomes) down the microscope, it is now possible to use a technique called ‘microarray’ which can do the analysis with 100 times greater depth than can be achieved using a microscope. The plus side is that the microarray technique can detect a far greater number of potentially important genetic differences; but a down side is that it can also detect many changes for which the impact on the health of the baby is unknown or uncertain.

Examples of genetic differences that carry certainty are major chromosome abnormalities such as the trisomies e.g. Down Syndrome, and deletions associated with severe intellectual disability in 100% of cases, e.g. 1p.36 deletion. Uncertain findings are the various small deletions and duplications that are known to only have an adverse outcome in 10-20% of people with them.

All participants were provided with a decision aid which described in detail the choice available in regards to the genetic information. The options were ‘targeted’, where only the information that would affect health of the baby was provided, or ‘extended’, where all information, even the uncertain aspects, was provided. Participants were asked to read the decision aid, complete a ten minute survey along with indicating their choice of genetic information. What did you find?

Response: A total of 111 pregnant women were recruited to this study. 66 participants (59.5%) chose to receive extended information and 45 participants (40.5%) chose targeted.

For those that chose to receive extended information, there was an association with mother’s having testing because of advanced maternal age, taking longer than 12 months to fall pregnant and being of Asian background.

For those who chose targeted information, there was an association with having testing because of an increased chance of having a baby with Down Syndrome on the basis of a screening test result. What should readers take away from your report? 

Response: Our results suggest that providing the option of receiving different information should be considered. We need to find a way to offer informed choice to pregnant women about the type of testing they want and how much information they want to receive. This will require a new model of care encompassing cooperative services between GPs, obstetricians, genetic counsellors and testing laboratories, with community and health professional education at the forefront – and of course funding.  The obstacles are not unsurmountable. What recommendations do you have for future research as a result of this work? 

Response: We need to implement a service model that allows for choice and evaluate educational materials (e.g. a decision aid)  that could make the task easier for those providing the services, both prior to any testing and following any adverse results that may be found. This is especially important as prenatal testing is evolving rapidly. Although currently available non-invasive prenatal testing (NIPT), a simple maternal blood test, focuses on just a handful of major genetic conditions, such as Down syndrome, this technique will include a much larger range of conditions before too long, many the same as those already seen with microarrays. The challenge of uncertain results will not go away in a hurry and is likely to increase.   


Offering pregnant women different levels of genetic information from prenatal chromosome microarray: a prospective study

Jane L. Halliday, Cecile Muller, Taryn Charles, Fiona Norris, Joanne Kennedy, Sharon Lewis, Bettina Meiser, Susan Donath, Zornitza Stark, George McGillivray, Melody Menezes, Sian K. Smith, Della Forster, Susan Walker, Mark Pertile & David J. Amor

European Journal of Human Genetics (2018) 

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