Ethnic variation in the size of infant at birth

The impact of ethnicity and other maternal factors (BMI, parity, glucose tolerance, gestational age) on the size of the infant at birth was investigated in a relatively low socioeconomic status, multi-ethnic population at San Francisco General Hospital. A sample of 2,069 infants born to mothers of black, non-Hispanic white, Hispanic, and Chinese descent and whose mothers had received prenatal care at San Francisco General Hospital were studied. Maternal size, pregnancy history, and blood glucose were determined prenatally at 26-28 weeks gestation. Anthropometry was performed on the infant within 72 hours of birth. Black and Chinese infants were the lightest in weight, while Hispanic infants were the heaviest. When correction was made for maternal factors black infants were shown to be significantly (P < .05) lighter in birth weight than non-Hispanic white, Chinese, or Hispanic infants. Black infants were also significantly shorter in birth length and smaller in chest circumference. Chinese infants had significantly (P < .05) greater adiposity, as indicated by the sum of skinfold measurements, than both black and Hispanic infants. These findings are relevant to current practices in neonatal growth categories which are determined solely by birth weight and do not account for variations in body composition. Comparisons with a relatively higher socioeconomic status sample from Kaiser-Permanente Hospital (Oakland) shows a similar prevalence of low birth weight among blacks. These results support other results that ethnicity is a major independent influence on the weight of the newborn.