4. Measuring Infant Length: Equipment and Preparation

Length, measured in the recumbent position, is the correct linear measurement for infants younger than 24 months of age or children aged 24 to 36 months who cannot stand unassisted.

Accurate length measurement requires a calibrated lengthboard with certain features for measuring length in the recumbent position.

The critical components of a lengthboard are 1) a fixed headpiece and 2) a moveable footpiece which is perpendicular to the surface of the table that the length board is on. Lengthboards are described in detail in the Accurately Weighing and Measuring: Equipment module.

It is important that infants be measured using procedures similar to those used in developing the charts. The NHANES length data were collected on infants wearing clean disposable diapers or diapers and undershirts.

Length measurements for infants and young children should be obtained while the child is dressed in light underclothing or a diaper. The child's shoes must be removed. Hair ornaments should be removed from the top of the head.

			Length is measured with a suitable measuring board
			Use a calibrated lengthboard with a fixed headpiece and movable footpiece which is perpendicular to the surface of the table
			Measure infant without shoes and wearing light underclothing or diaper