More Babies are Being Born with Down Syndrome
A growing number of children in the U.S. are being born with Down syndrome so says a federal researcher. It appears the main reason is that older women are having babies. Data collected from 10 regional registries of birth defects is showing that the incidences of Down syndrome among U.S. children increased by 31 percent between 1979 and 2003.
"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 occurrences 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.
The study also showed that Down syndrome prevalence at birth was consistently higher among non-Hispanic whites than among non-Hispanic blacks. In addition the study showed that Down syndrome prevalence was consistently higher among males than females, regardless of race, ethnicity, or age group.
Down syndrome transpires when a baby has an extra chromosome, number 21 of the 23 that determine genetic characteristics. Most people believe that the syndrome is a cause of mental retardation, however, some children with Downs 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.
Dr. Correo stated that these 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."