Increase in Babies Born With Down Syndrome
Researchers Say Rise Could Reflect the Growing Proportion of Births to Older Mothers
Nov. 30, 2009 -- The prevalence of infants born with Down syndrome has increased
dramatically in recent years, new research indicates.
Reporting in the Nov. 30 issue of Pediatrics, scientists say the
prevalence of live born infants with Down syndrome increased by 31% between
1979 and 2003, from 9 to 11.8 per 10,000 live births in the 10 U.S. regions
That represents an average increase of 0.9% per year, the study shows.
The researchers analyzed data from 10 population-based birth registries in
the U.S., estimating prevalence at birth among children up to age 19 in each
region, and also in all of the areas together.
During the periods studied, "prevalence at birth significantly increased
among births to older mothers and decreased slightly among births to younger
Maternal age (age 35 and older) is a known risk factor for having a child
with Down syndrome, the most common chromosomal disorder.
"The overall [Down syndrome] prevalence at birth was almost five times
higher among births to older mothers (38.6 per 10,000) than among births to
younger mothers (7.8 per 10,000)," the researchers write.
The study also shows that:
- Down syndrome prevalence at birth was consistently higher among
non-Hispanic whites than among non-Hispanic blacks.
- Down syndrome prevalence was consistently higher among males than females,
regardless of race, ethnicity, or age group.
- In 2002, Down syndrome was present in one of every 971 children and
adolescents up to age 19, living in the 10 regions studied.
"Our study also confirmed an increase in prevalence in [Down syndrome] at
birth over time, and this trend over time paralleled the increasing proportion
of births to older mothers," the researchers write.
The researchers say their findings could reflect an increasing proportion of
births to older mothers, and improvements in the survival of infants with the
genetic disorder. People with Down syndrome are at increased risk for medical
problems such as heart defects, hearing and vision problems, and respiratory
The number of children, adolescents, and adults with Down syndrome is likely
to increase and people with the condition are likely to live longer, the
The authors say in a news release that their findings may be useful in
determining the number of people with Down syndrome and in the development of
policies to help them.