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Library of Medicine®| On this page: Reviewed March 2012 What is
trisomy 18? Trisomy 18, also called Edwards syndrome, is a
chromosomal condition associated with abnormalities in many
parts of the body. Individuals with trisomy 18 often have slow
growth before birth (intrauterine growth retardation) and a low
birth weight. Affected individuals may have heart defects and
abnormalities of other organs that develop before birth. Other
features of trisomy 18 include a small, abnormally shaped head;
a small jaw and mouth; and clenched fists with overlapping
fingers. Due to the presence of several life-threatening medical
problems, many individuals with trisomy 18 die before birth or
within their first month. Five to 10 percent of children with
this condition live past their first year, and these children
often have severe intellectual disability. How common is trisomy
18? Trisomy 18 occurs in about 1 in 5,000 live-born infants; it
is more common in pregnancy