4. Measuring Infant Length: Procedures

The child should be placed on his back in the center of the length board so that the child is lying straight and his shoulders and buttocks are flat against the measuring surface. The child's eyes should be looking straight up. Both legs should be fully extended and the toes should be pointing upward with feet flat against the footpiece.

Accurate length measurements require two measurers. One measurer holds the infant’s head, with the infant looking vertically upward and the crown of the head in contact with the headpiece in the Frankfort Horizontal Plane. The head of the infant is firmly but gently held in position. The measurer gently cups the infant’s ears while holding the head. Make sure the infant's chin is not tucked in against his chest or stretched too far back.

		What is the Frankfort horizontal plane?

While the second measurer holds the infants head in the proper position, the measurer aligns the infant’s trunk and legs, extends both legs, and brings the footpiece firmly against the heels. The measurer places one hand on the infant’s knees to maintain full extension of the legs. The infant’s toes are pointing upward.

It is imperative that both legs be fully extended for an accurate and reproducible length measurement. If only one of the infant’s legs is extended during the length measurement, the measurement may be unreliable and inaccurate. Correctly positioning the infant for a length measurement generally cannot be accomplished without two measurers.

Parents may participate in the length measurement [between the two trained measurers] to provide reassurance and security to the infant.

Should length or stature be measured for a child aged 24 to 36 months? The best guideline is to think about the physical abilities of the child. Generally, if the child can stand unassisted and follow directions for proper positioning, a stature measure should be taken. However, if there are concerns about the child's growth and the previous measure was length, then length should be measured again. (See the CDC training materials: Case Example 5 for more information about transitions between charts.)

Maintaining a record of the child’s length on the "Birth to 36 months" chart may be helpful in circumstances where it is necessary to monitor small increments of growth.