Rise in number of Down’s syndrome cases as women wait longer to start families

October 27, 2009 by Shawn Douglas
Filed under: News

Down’s syndrome cases have become more common over the last two decades but have been offset by better early detection and an increase in terminations.

The British Medical Journal published a paper today indicating that diagnoses of Down’s syndrome has increased by 71 percent since 1989, yet the rate of babies actually born with Down’s has remained nearly steady over the same time period.

Researchers from Barts and the London School of Medicine found that diagnoses in women over the age of 37 rose significantly, likely due to the combination of more accurate tests and wider adoption of early screening.

“Increases in maternal age would have caused a 48 per cent increase in births with Down’s syndrome in the absence of terminations between 1989/91 and 2005/7,” said the researchers.

‘”However, terminations of Down’s pregnancies due to an increase and improvements in antenatal screening have caused the number of live births with Down’s remain constant.”

With the number of women opting to wait until their 40s nearly doubling in the last ten years, there is a corresponding increased risk for Down’s syndrome—a nearly 16 times greater chance for a woman of 40 than a woman of 25.

“I don’t think the message is getting through about the high risk of having a baby with Down’s in your 40s,” said Dr. Maggie Blott, spokesperson for the Royal College of Obstetricians and Gynecologists.

“There are enormous challenges for women whether they decide to have the baby, who will have long-term health needs, or have a termination of an often much-wanted child at a stage in life when it will be ever harder to become pregnant.’

The researchers were also surprised to find that only 70 percent of women who gave birth to a Down’s syndrome baby were actually screened, suggesting to them that “a considerable proportion of women may still decide not to be screened.”

They suggested that with less invasive procedures that don’t risk miscarriage, more women may opt for screenings.