The choice to undergo prenatal testing is a big one. Here's what you should consider before making the decision
Cindy Babcock, of Peterborough, Ont., has known since the age of four she is a carrier for a rare metabolic disorder. Cindy’s mother gave birth to two baby boys after Cindy was born — both died within three days. Her mother, a nurse, refused to accept the diagnosis of SIDS and pushed for answers. Doctors finally determined that the boys had died from ornithine transcarbamylase deficiency (OTC). “In normal people, food intake changes into ammonia, and then from ammonia into urine,” explains Babcock. “But with OTC, it does not get past that ammonia stage, so the body basically gets poisoned.”
Babcock chose to be tested for OTC when she became pregnant with her daughter, Natasha, 10 years ago, even though she knew that she would carry the pregnancy to term, no matter what. After a specialized test that was part of her amniocentesis, she was thrilled to learn that Natasha did not have OTC — in fact, she wasn’t even a carrier. “It was the best news,” says Babcock. Several years later, however, Babcock became pregnant again. And this time the news was not so good. Born with OTC, her baby boy, Colin, lived for just three days. Babcock takes comfort in knowing that “he was loved the whole time” and he died surrounded by friends and family. “It may have been a short life, but it was still a life,” she says.
Her situation brings up one of the misconceptions regarding prenatal testing, says Doug Wilson, a reproductive geneticist and department head of obstetrics and gynaecology at the University of Calgary. All prenatal tests are optional and “people think that if you have no intention of terminating a pregnancy, there’s no reason to have prenatal testing,” he says. “But the tests have nothing to do with the choices you make afterward.”
Even if you’re planning to continue your pregnancy, says Wilson, it’s important to know whether your child has a chromosomal abnormality or another genetic condition “because it’s going to improve the care that your fetus gets.” You might choose to deliver in a hospital that has specialized facilities available, for example, and you get the opportunity to prepare yourself and your partner, family and friends in advance.
The field of genetic testing is getting more sophisticated all the time. Here’s a guide to what the various prenatal tests are supposed to determine and why you might want to know.