Data from a longitudinal study of 680 babies (345 females and 335 males) born in a little town of Northern Italy (Faenza, near Ravenna) were used to test relationships between physical growth during the first three years of life and gestational age, breast feedinf and other important determinants. Children born before 38 weeks of gestation tended to show greater increments in weight and length during the first year of life. The results indicated that the biological traits effects were more important than social factors for growth in weight and length. The comparison of our data with previous ones on Italian babies suggested that there has been a trend in infant dimensions during the last 30 years.