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Egenis · News

Testing times

28.10.2009

Introduction

Susan Kelly reflects on a rise in prenatal diagnoses of Down's

Story

The number of Down’s Syndrome diagnoses has risen sharply over the last 20 years as women have opted to put off having children until later in life, according to a new report by researchers at Queen Mary, University of London, published in the British Medical Journal this week. The report is based on analysis of the National Down Syndrome Cytogenetic Register that holds details of antenatal and postnatal diagnoses of Down’s Syndrome made by all cytogenetic laboratories in England and Wales since 1989.

“Over the same period, there have been major improvements in pre-natal screening for the condition and an increase in the number of women being screened,” the report notes, adding, “The proportion of couples diagnosed with a Down’s Syndrome pregnancy who decide to terminate has also remained constant at 92 per cent.” The implication, therefore, is that the number of terminations following a positive prenatal diagnosis of Down’s Syndrome has risen as well. Further, the researchers report that among women aged 37 and older, a fairly consistent 70% of Down’s Syndrome pregnancies were diagnosed prenatally. This means that roughly 30% of Down’s Syndrome pregnancies among women in this age group were not detected prenatally, either because they were missed in screening (false negative rates) or because a sizeable minority of women did not undergo screening and diagnosis. This may reflect that later life pregnancies are often particularly wanted, leading some prospective parents to, as Egenis Senior Research Fellow Dr Susan Kelly has identified, ‘choose not to choose’ by not engaging in prenatal screening, with subsequent further decisions about diagnosis and termination.

"By contrast, researchers reported a large increase – from 3% to 43% - in diagnosis of Down’s Syndrome among younger pregnant women," writes Dr Kelly. "While presented largely in terms of the successful expansion and reach of antenatal screening practices for Down’s Syndrome in England and Wales, it is important to note that this dramatic rise has occurred with very little public debate about the ethical and social implications of expanded screening. The report notes that, “In the absence of such screening, numbers of live births with Down’s syndrome would have increased by 48% (from 959 to 1422), since couples are starting families at an older age.” This implies a settled societal consensus that effort and resources be increasingly directed toward avoiding a rise in the numbers of children born with a Down’s Syndrome diagnosis, a consensus for which there is no real evidence.

"Debate about prenatal screening and diagnosis has largely centered on mechanisms to ensure adequate provision of information prior to prospective parents accepting and undergoing a screening procedure, including information that a screening test may lead to a further decision about pregnancy termination. At least some elements of this debate are concerned with whether information about raising a child with Down’s Syndrome is adequately conveyed to prospective parents, and what such information should comprise. These questions suggest that perhaps there should be further discussion regarding how and why prenatal screening expansion in the UK takes place, for what conditions, and within what contexts.

"A consensus does appear to exist within the medical community that the informed choice of prospective parents presented with options of prenatal screening and diagnosis must be fostered and protected. As prenatal testing moves toward safer and earlier non-invasive procedures, questions about the nature of ‘informed choice’ and the ethical basis and contexts of screening provision will become both more pressing and more difficult.

"Non-invasive prenatal testing offers the potential for streamlining the testing procedure from a process involving two separate steps – initial screening and possible further diagnosis – to a single step. Choosing to offer non-invasive prenatal testing in this way would clearly reduce opportunities for the exercise of informed choice. Current systems for the counselling and support of parents offered pre-natal testing are generally excellent. Care must be taken at least to maintain, if not improve and rethink, these processes within the drive toward the expansion and less risky administration of prenatal testing. Reports such as this suggest that the time for such societal scrutiny is now."

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Chromosome