Microcephaly Primary microcephaly 2012-03-18T06:50:36Z Small cranium present at birth UMLS:C4020749 Decreased head circumference present at birth Small head present at birth Microcephaly present at birth Small head circumference present at birth Congenital microcephaly Head circumference below 2 standard deviations below the mean for age and gender at birth. Head circumference small for gestational age Congenital small head Congenital small head circumference UMLS:C2677180 HP:0011451 Small skull present at birth Congenital small skull Congenital decreased head circumference