A new generation of simple blood tests is allowing would-be parents to learn about the sex and potential genetic anomalies of their babies in the first trimester, a stage of the pregnancy when it's relatively easy to get an abortion in Canada.
Known as non-invasive prenatal testing (NIPT), the approach has the advantage of giving some women more time to make decisions about their pregnancies, while helping others to avoid unnecessary invasive procedures such as amniocentesis, which carry a small risk of miscarriage.
But NIPT also raises difficult ethical questions, especially among opponents of sex-selective abortion and people with Down syndrome, who fear NIPT will make it easier to screen their condition out of future generations.
Complicating matters further, for-profit genetic testing companies are, in some cases, offering to screen for conditions that are much rarer than Down syndrome and therefore harder to reliably detect.
"There is some concern that because it's a very good test, doctors and patients would consider it a 100-per-cent reliable test that could replace amniocentesis or other invasive tests, which is not true," said Dr. Audibert, who is also one of the lead authors of a new prenatal screening guideline published in September by the Society of Obstetricians and Gynaecologists of Canada and the Canadian College of Medical Geneticists.
That caveat is even more important when NIPT is used to detect rarer genetic conditions such as trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome) or Turner syndrome, a condition that arises when a female is missing all or part of the X chromosome, which helps to determine the sex of a fetus.
The waters get even murkier when it comes to screening for a slew of different microdeletion syndromes, which occur when a small segment of a chromosome is missing.
Several companies already offer microdeletion screening to women who can pay, but the new Canadian guidelines recommend against it, saying there isn't enough good evidence that cfDNA can reliably detect microdeletions.
Vardit Ravitsky, a professor of bioethics at the University of Montreal, predicted it won't be long before the companies vying for dominance of the NIPT market begin to offer screening for dozens more potential genetic flaws whose effects on a baby's future health are unclear.
In the meantime, doctors, ethicists, pregnant women and their partners are wrestling with the choices NIPT already provides.