THE NUMBER of women in England and Wales conceiving babies with Down syndrome has increased by more than 70 per cent in the last 20 years, but more than 90 per cent of women affected are having abortions, according to the latest research.
In screenings offered to mothers during pregnancies, 1,843 cases of Down syndrome were diagnosed, up from 1,075 in 1989/90 but the number of births actually fell from 752 to 743.
“In the absence of such screening, numbers of live births with Down syndrome would have increased by 48 per cent (from 959 to 1,422), since couples are starting families at an older age,” said Prof Joan K Morris of Queen Mary’s University, London.
In women aged over 37, doctors were able to give antenatal notice that the foetus had Down syndrome, while the number diagnosed in younger women rose from 3 per cent to 43 per cent, due to more sophisticated screening.
Only 8 per cent of couples in England and Wales diagnosed with a Down syndrome pregnancy decide to continue with the pregnancy, with the rest opting for abortion. This figure has remained constant over the decades.
Results of the study, which examined trends in Down syndrome live births and antenatal diagnoses in England and Wales from 1989 to 2008, were published in the British Medical Journal.
“The proportion of antenatal diagnoses has increased most strikingly in younger women, whereas that in older women has stayed relatively constant. This trend suggests that, even with future improvements in screening, a large number of births with Down syndrome are still likely, and that monitoring of the numbers of babies born with Down syndrome is essential to ensure adequate provision for their needs,” the study reported.
The statistics reflect changing lifestyles. Women who become pregnant in their 40s have a 16 times greater chance of having a Down syndrome child than a woman who gives birth during her mid-20s. Official figures from the Office of National Statistics show that nearly half of all births in England and Wales were to women aged over 30, compared to just 28 per cent in 1986.
The greatest jump has taken place among women aged between 35 and 39, while the percentage of births to women over 40 has more than tripled in just 13 years – from 1.1 per cent of all births in 1996 to 3.5 per cent in 2006.
One-third of all women choose not to have the screening test, and this figure, too, has remained stable over the two decades, despite the fact that the screening test has become both more sophisticated and safer.
In 1989, the only test that could be offered to pregnant women over 35 was an amniocentesis test whereby the amniotic fluid surrounding the foetus is removed using a fine needle and subsequently examined for signs of the condition.
Though it is judged to be accurate, it provokes a miscarriage in approximately 1 per cent of cases. So it is usually reserved for potentially high-risk cases – older women and those who have already had a Down’s child.