Objectives: To compare the growth profiles of infants and young children born small for gestational age (SGA, < 10th percentile birth weight for gestation) or large for gestational age (LGA, > or =90th percentile) with those appropriate for gestational age, and to document the expected growth patterns through early childhood based on national health examination survey data.
Sample: Infants and children, 2 to 47 months of age, who were born in the United States and examined using the Third National Health and Nutrition Examination Survey (1988-1994).
Main outcome measures: Measurements of growth status based on normalized distributions (z scores or standard deviation units [SDUs] for weight, length, and head circumference.
Results: Prevalence rates were as follows: SGA infants, 8.6%; appropriate for gestational age infants, 80.9%; and LGA infants, 10.5%. Infants who were SGA appeared to catch up in weight in the first 6 months, but thereafter maintained a deficit of about -0.75 SDUs compared with infants who were appropriate for gestational age. The weight status of LGA infants remained at about +0.50 SDUs through 47 months of age. Length and head circumference were also associated with birth weight status, averaging over -0.60 SDUs for SGA infants and +0.43 SDUs for LGA infants.
Conclusions: Birth weight status is related to growth rates in infancy and early childhood, which underscores the importance of considering child growth relative to birth status when using growth charts. Small for gestational age infants remain shorter and lighter and have smaller head circumferences, while LGA infants grow longer and heavier and have larger head circumferences.