Expert attributes rise to more women having babies later in life
MONDAY, Nov. 30 (HealthDay News) -- A growing number of children in the United States are being born with Down syndrome, federal researchers say.
The overriding reason, experts add, is that more older women are having babies.
Data from 10 regional registries of birth defects show that the incidence of Down syndrome among U.S. children increased by 31 percent between 1979 and 2003, from 9.0 to 11.8 per 100,000 live births.
The survey of U.S. children with Down syndrome provides a benchmark for determining whether adequate health services for them are being provided, the researchers say.
"In the past we have focused on the prevalence at birth," said Dr. Adolfo Correa, a supervisory medical officer with the U.S. Centers for Disease Control and Prevention and lead author of the report, published online Nov. 30 in Pediatrics. "The survival of children with Down syndrome has improved over the years, so we were interested in knowing the prevalence among children."
The growing incidence, however, could paint a false picture, said Dr. Siobhan Dolan, an associate professor of obstetrics and gynecology and women's health at Albert Einstein College of Medicine and Montefiore Medical Center in New York City and a consultant to the March of Dimes Birth Defects Foundation.
The increase simply reflects the fact that more American women are having babies later in life, and "there is a strong epidemiological association between Down syndrome and maternal age," Dolan said.
Down syndrome occurs when a child has an extra chromosome, number 21 of the 23 that determine genetic characteristics. Though most people think of the syndrome as a cause of mental retardation, some children with Down do not need special schools, Dolan said. But the extra chromosome is associated with a number of major physical problems, including life-threatening heart abnormalities.
The numbers in the new study "allow us to plan for Down syndrome, to see what is working for the children, including cardiac surgery to extend the life span," she said.
Correo said the findings will help determine "whether the availability of specialty services will be enough to meet the needs of the Down syndrome population."
The increased number of people with Down syndrome reflects "an accomplishment in our health system that should be noted," Dolan said. "The care for Down syndrome individuals is probably improving, so that life expectancy is improving."
Studies of the relationship between maternal age and the incidence of Down syndrome are continuing, she said. "That is the subject of very active research -- what causes chromosomes to divide abnormally at certain ages. The genetics is really interesting."
Tests to detect chromosomal abnormalities during pregnancy now are widely available, Dolan said. Such tests "can allow us to plan for health care, to plan for delivery, having a cardiology team there to care for the child," she said.
A number of organizations provide advice and services for families with children who have Down syndrome, she said. "Getting educated from other families and support groups is an important asset," she said.
Dolan also noted, however, that the data in the federal study now are now nine years old. "It is not 2009 data, and this is a continually changing field," she said. "It is going to be interesting to see what happened between 2003 and 2009."
The U.S. National Institute of Child Health and Human Development has more on Down syndrome.
By Ed Edelson
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