Graph description: Figure 4. Centile chart of fetal head circumference by gestational age

This is a chart with six curved lines. The horizontal axis shows gestational age in weeks, labeled 15, 20, 25, 30, 35, and 40. The vertical axis shows head circumference in millimetres, labeled 100, 150, 200, 250, 300, 350, and 400. The six lines are in three pairs. In each pair the upper line is solid and represents males, the lower line is broken and represents females. The lowest pair is labeled 5%, the middle pair is labeled 50%, the uppermost pair is labeled 95%, The lines start at the bottom left corner of the graph and rise in an almost straight line at first, the slope being about 15 millimetres per week of gestational age. The lines diverge slightly as they rise. Then the slope becomes less steep and the lines curve gently to a more and more gentle rise.

Back to Measurement in Health and Disease: Reference Intervals and Centile Charts.

This page maintained by Martin Bland.
Last updated: 8 May, 2008.