New research has revealed that due to an increasing amount of women waiting longer to start a family, there has been a steep rise in the number of Down’s pregnancies.
Over the last two decades there has been a 71 per cent increase in Down’s pregnancies, showing the trend for women choosing to wait until their late thirties and early forties to reproduce. However, advances in pre-natal screening allow earlier detection of Down’s, and ultimately more terminations.
The number of babies actually being born with Down’s syndrome has therefore kept on an even keel, at approximately 750 a year, give or take 20 per cent over some years.
The new figures, published in the British Medical Journal, displays how risky it can be for women to wait too long. Between 1989 and 2006, the number of women conceiving over the age of 35 went from 6 per cent to 15 per cent - while those waiting until after 40 is increasing at an even greater rate. A mother waiting until the age of 40 to have a baby has a 16 times bigger risk of conceiving a Down’s baby, compared to a 25 year old.
Joan Morris, professor of medical statistics at Queen Mary, University of London, said, “There has been an enormous shift in the age of mothers. It really has been dramatic. Down’s is the commonest chromosomal abnormality in babies and the commonest abnormality of any kind in babies born to mothers over 45.”
In 1989-90 there were 1,075 Down’s pregnancies, compared to 1,843 in 2007-8. Based on the rise of maternal age, there would have been a 48 per cent increase of Down’s babies born, had none been terminated. However, the birth rate actually fell by 1 per cent due to the advances in pre-screening. Professor Morris said, “The proportion of women who had a termination has not changed since 1989, at 92 per cent of those who had an antenatal diagnosis.”
Everyone is routinely offered the screening, but the number of women older than 37 agreeing to have it stayed the same over the last two decades, at 20 per cent. Professor Morris said, “Twenty years ago we were picking up 70 per cent of Down’s syndrome babies and today we are still picking up 70 per cent. Now we have got the option of non-invasive screening tests [blood samples and ultrasound] but there is still a core group of women who don’t want screening. There is a proportion who will always say no.”
Within women under the age of 37, the number of Down’s pregnancies being picked up rose from 3 per cent to 43 per cent in the same time, due to the development of screening methods. Professor Morris said, “As the test improves we may get near 70 per cent of babies detected, but I don’t think we will make 100 per cent.” She added that it was necessary to determine why women are turning down screening.
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New research has revealed that due to an increasing amount of women waiting longer to start a family, there has been a steep rise in the number of Down’s pregnancies.
Over the last two decades there has been a 71 per cent increase in Down’s pregnancies, showing the trend for women choosing to wait until their late thirties and early forties to reproduce. However, advances in pre-natal screening allow earlier detection of Down’s, and ultimately more terminations.
The number of babies actually being born with Down’s syndrome has therefore kept on an even keel, at approximately 750 a year, give or take 20 per cent over some years.
The new figures, published in the British Medical Journal, displays how risky it can be for women to wait too long. Between 1989 and 2006, the number of women conceiving over the age of 35 went from 6 per cent to 15 per cent - while those waiting until after 40 is increasing at an even greater rate. A mother waiting until the age of 40 to have a baby has a 16 times bigger risk of conceiving a Down’s baby, compared to a 25 year old.
Joan Morris, professor of medical statistics at Queen Mary, University of London, said, “There has been an enormous shift in the age of mothers. It really has been dramatic. Down’s is the commonest chromosomal abnormality in babies and the commonest abnormality of any kind in babies born to mothers over 45.”
In 1989-90 there were 1,075 Down’s pregnancies, compared to 1,843 in 2007-8. Based on the rise of maternal age, there would have been a 48 per cent increase of Down’s babies born, had none been terminated. However, the birth rate actually fell by 1 per cent due to the advances in pre-screening. Professor Morris said, “The proportion of women who had a termination has not changed since 1989, at 92 per cent of those who had an antenatal diagnosis.”
Everyone is routinely offered the screening, but the number of women older than 37 agreeing to have it stayed the same over the last two decades, at 20 per cent. Professor Morris said, “Twenty years ago we were picking up 70 per cent of Down’s syndrome babies and today we are still picking up 70 per cent. Now we have got the option of non-invasive screening tests [blood samples and ultrasound] but there is still a core group of women who don’t want screening. There is a proportion who will always say no.”
Within women under the age of 37, the number of Down’s pregnancies being picked up rose from 3 per cent to 43 per cent in the same time, due to the development of screening methods. Professor Morris said, “As the test improves we may get near 70 per cent of babies detected, but I don’t think we will make 100 per cent.” She added that it was necessary to determine why women are turning down screening.
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