Use of the Weaver curve in a child with macrocephaly

Plotted above is an example of the use of the Weaver curve. The child's OFC was 49.5 cm at the age of nine months, placing him well above the 97^th percentile on Nellhaus's head circumference chart. His SS was calculated to be +2.93. The father had an OFC of 59.5 cm, and the mother's was 59.0 cm with SS of +2.65 and +2.90, respectively. Their average parental SS was +2.78. When plotted, the intercept (point A) of lines from the SS falls below the +2 SD regression line. Thus, the child's head size in relationship to that of his parents is judged to be normal.