Doctors are being urged to help pregnant women get themselves ready for bad news about their health which can emerge accidentally from tests on their babies.
Modern prenatal tests can spot genetic problems in babies from fragments of their DNA that leak into the mother’s bloodstream. But the same tests can reveal unknown health problems in mothers themselves, from early stage cancer to genetic disorders.
Doctors have used the tests since 2011, but the unexpected consequences have only come to light as more women have had the procedure. Since late 2014, at least 26 pregnant women with abnormal test results have later found out that they have cancer. In ten cases, the prenatal test results raised doctors’ suspicions and ultimately led to the diagnosis.
Writing in the journal Nature, Diana Bianchi, director of the Mother Infant Research Institute at Tufts Medical Center in Boston, calls on doctors who provide the tests to make sure women are better informed, and have counselling, before undergoing testing.
“Parents, obstetricians and physicians have been taken by surprise,” Bianchi writes.
“Consent forms used by test providers rarely mention the possibility of findings concerning the mother’s health.”
In the US, doctors take DNA from the mother and the placenta and compare it with a healthy reference genome. The procedure allows clinicians to check whether cells have the wrong number, or fragmented, chromosomes, the strands of genetic material that hold a person’s genes. Abnormal test results often mean that the baby has a medical problem, but sometimes it is the mother’s DNA that bears the fault.
In cases made public so far, some pregnant women have learned they have a sex chromosome abnormality that affects their fertility. Others have been diagnosed with DiGeorge syndrome, a genetic disorder that causes learning difficulties, heart defects and immune problems. But more conditions may come to light. “Clinicians have yet to discover all that non-invasive prenatal testing can reveal about mothers,” Bianchi writes.
While the tests are available in the UK, they are used in a targeted fashion that reduce the chances of doctors finding out much about the mother’s health, said Sadaf Ghaem-Maghami, chair of the Royal College of Obstetricians and Gynaecology’s science advisory committee. For example, the test might check specifically for chromosomal defects that cause Down’s syndrome, rather than screen for all genetic abnormalities.
Bianchi argues that pregnant women should be required to sign consent forms that state explicitly that unexpected results could emerge. Women could have the chance to opt out of being told certain information: for example, that they have chaotic DNA patterns suggestive of a tumour. At the same time, doctors need to learn more about the medical problems that such tests can reveal.
“Handled properly, the incidental findings emerging from prenatal tests could accelerate treatments and save lives – rather than just increase the anxiety of thousands of pregnant women,” Bianchi writes.
