of 48 defect categories evaluated , 46 were associated with excess intrauterine growth retardation , most notably chromosomal anomalies ( eg , 83.7 % for infants with trisomy 18 , relative risk 46 ) and anencephaly ( 73.3 % , relative risk 25 ) .
C0008625
chromosomal anomalies
C0152096
trisomy 18