Reference data for head circumference-for-length in preterm low-birth-weight infants

Objective: To provide reference data for head circumference-for-length in preterm low-birth-weight infants that are independent of age, but extend for the ranges of head circumference (34-49 cm) and length (52.0-102.9 cm) values found from birth to 36 months of gestation-adjusted age. Design: Measurements were made at 9 ages in 867 preterm infants in the Infant Health Development Program, a randomized clinical trial that included various ethnic groups at 8 sites. At birth, two thirds of the infants weighed less than 2000 g, and one third weighed between 2000 and 2500 g. Measurements were taken at birth, at 40 weeks of postconceptional age, and at 4, 8, 12, 18, 24, 30, and 36 months of gestation-adjusted age. A model fitted to the serial data for each infant was used to estimate head circumference and length from 36 weeks after conception to 36 months of gestation-adjusted age. Results: Tables and charts of means and SDs and selected percentiles for each sex were made. These tables and charts are for very low- (less than or equal to 1500 g) and low-birthweight (1501-2500 g) infants by 3-cm intervals of length. Conclusion: These tables and charts should assist clinicians in evaluating and monitoring head circumference in preterm low-birth-weight infants by taking body length into account.