Diana W. Bianchi in Nature:
A healthy pregnant woman has a blood test to rule out the possibility that her baby has certain abnormalities, such as Down's syndrome. One week later, a genetic counsellor calls her and recommends a follow-up test such as amniocentesis. When the counsellor calls again, she says that the baby is healthy but that the mother needs to be screened for cancer. Since 2011, clinicians have been able to analyse the genome of a fetus by sequencing DNA fragments found floating in the mother's blood. With the use of these non-invasive prenatal tests soaring (see 'Test scores'), mothers are increasingly facing unexpected, 'incidental' findings about their own health. As of late 2014, at least 26 pregnant women with abnormal blood-test results later learned that they had cancer1. In 10 of them, the prenatal tests prompted the medical assessments that revealed this; in the other 16, the cancers were not discovered until the mothers developed symptoms.
Parents, obstetricians and physicians have been taken by surprise. Consent forms used by test providers rarely mention the possibility of findings concerning the mother's health. And caregivers have little guidance on what to do when such findings arise. Test providers need to rethink their consent forms to prevent unwarranted confusion and anxiety — not least, women deciding to terminate their pregnancies on the basis of wrong interpretations of test results2. And professional societies, such as the American College of Medical Genetics and Genomics (ACMG), the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine (SMFM), need to take the lead on providing education and clinical guidance.