Social, demographic pattern and aspects of medical care were studied in a population of 9048 living births (98% of the universe), at Ribeirão Preto, SP, Brazil, from June 1978 to May 1979 Data was obtained about fathers and mothers, such as: age, degree of education, smoking habit, work, marital status, frequency and duration of pregnancies, prenatal and natal care, delivery type, children (sex, weight, height, head circumference at birth and infant mortality), social class, family income and place of residence. It was observed an important reduction in infant mortality when comparing 69-70 and 78-79 studies (p<0.01), and a strong correlation of risk factors (perinatal health) with social patterns. Such data are under careful analysis.
