Very Low Birthweight Down Syndrome Infants at High Risk for Heart, Lung Disorders
Posted Nov 22 2010 10:53am
Very low birthweight Down syndrome infants are at higher risk for disorders of the heart
and lungs than are very low birthweight infants who do not have a chromosomal
variation, according to a study by a National Institutes of Health research
The study was conducted by researchers in the Neonatal Research Network
of the NIHs Eunice Kennedy Shriver National Institute of Child Health
and Human Development (NICHD) and was published online in Pediatrics.
The researchers sought to identify health concerns unique to this group
of infants, to inform their care and treatment.
Very low birthweight (VLBW) infants are those weighing less than 3.5
pounds. The principal causes of very low birthweight are preterm birth
and failure to grow in the uterus. Low birthweight infants are at increased
risk for death during infancy and for such health complications as cerebral
palsy, learning disabilities, heart disorders and breathing problems.
The researchers found that VLBW Down syndrome infants had more than
twice the risk of death during infancy as VLBW infants born without a
birth defect or chromosomal variation. The increased risk of death was
due in part to the more frequent occurrence of conditions affecting the
heart, lungs and digestive tract among the Down syndrome infants, and
the greater likelihood of a life-threatening blood infection. VLBW Down
syndrome infants were less likely to develop retinopathy of prematurity
( http://www.nei.nih.gov/health/rop/rop.asp ), an overgrowth of blood vessels
in the retina, which can affect vision.
"Previously, health professionals caring for very low birth weight Down
syndrome infants had to base treatment decisions on studies of the general
population of very low birth weight infants and on studies of infants
with Down syndrome who may not have been of low birthweight," said senior
author Rosemary D. Higgins, M.D., of the NICHD. "Our study provides
much needed information for practitioners and families making treatment
decisions for this unique group of patients."
With Down syndrome, an extra copy of chromosome 21 results in a distinctive
set of mental and physical symptoms. (http://www.nichd.nih.gov/health/topics/down_syndrome.cfm)
Over a period of 15 years, the researchers analyzed the medical records
of more than 50,000 infants born weighing between .875 and 3.5 pounds.
The researchers compared rates of survival and the prevalence of eye,
digestive, and lung complications among infants with Down syndrome, infants
with certain chromosomal variations other than Down syndrome, infants
with non-chromosomal birth defects and those without birth defects or
chromosomal variations. The researchers collected information from the
22 medical centers that make up the NICHD's Neonatal Research Network.
The study's lead author was Nansi S. Boghossian, M.P.H., of the University
of Iowa, Iowa City.
"Our analysis encompasses the largest group of very low birth weight
Down syndrome infants ever studied, " Boghossian said.
The researchers found that VLBW Down syndrome infants were about 2.5
times more likely to die in infancy than were VLBW infants who did not
have a chromosomal variation or a birth defect. This increased risk was
attributed in part to a greater likelihood of patent ductus arteriosis
(a malformation of the heart), bronchopulmonary dysplasia (a lung disorder
that may impair breathing), necrotizing enterocolitis (a serious inflammation
of the bowel) and sepsis (an infection of the blood). Infants with Down
syndrome had roughly the same chance for survival as did infants with
non-chromosomal birth defects.
The researchers also found that the Down syndrome infants in the study
were much less likely than all other infants to develop retinopathy of
prematurity. Previous studies have indicated that genes found on chromosome
21 may slow blood vessel growth. These genes are believed to influence
the growth of blood vessels in tumors, and individuals with Down syndrome
are less likely to develop tumors than are other individuals. These same
genes may protect Downs infants from blood vessels overgrowth in retinopathy
of prematurity. The authors added that future research on Down syndrome
infants reduced risk for retinopathy of prematurity might provide new
insights into this disorder affecting the retina.
The NICHD sponsors research on development, before and after birth;
maternal, child, and family health; reproductive biology and population
issues; and medical rehabilitation. For more information, visit the Institutes
Web site at http://www.nichd.nih.gov/ .
The National Institutes of Health (NIH) — The Nation's Medical
Research Agency — includes 27 Institutes and Centers and is
a component of the U.S. Department of Health and Human Services. It is
the primary federal agency for conducting and supporting basic, clinical
and translational medical research, and it investigates the causes, treatments,
and cures for both common and rare diseases. For more information about
NIH and its programs, visit www.nih.gov .