 The participants were 46 mothers and their term infants, 20 of whom were classified as appropriate for gestational age AGA, birth weight 2800 g at 37 weeks of gestation and 26 of whom were classified as small for gestational age SGA, birth weight 2500 g at 37 weeks of gestation. Gestational age was assessed by ultrasonography at 32 weeks of gestation. Only mothers who were planning to breast feed exclusively for at least four months were included in the study. Mothers with pregnancy-induced hypertension, multiple pregnancies, known HIV or hepatitis B infection, or use of tobacco products or alcohol were excluded from the study, as were infants with congenital abnormalities, chronic infections, or acute illnesses at the time of enrollment. 