The Pima Infant Feeding Study: breast feeding and gastroenteritis in the first year of life.

In 1978, a retrospective study of infant feeding was conducted among 257 Pima Indian women of reproductive age, who were residing on the Gila River Reservation, Arizona. With data on infant feeding patterns from 683 infants born 1950-1977 to the Pima Indian women, infants were classified into one of five feeding groups based on the duration breast-fed and time of introduction and duration bottle-fed. History of severe diarrhea/diarrhea with dehydration/diarrhea and vomiting was abstracted from the infant's medical record and classified as a case of gastroenteritis. The risk of developing a first such episode during the first year of life was compared between the exclusively bottle-fed and each of the other four feeding groups. The odds ratio of gastroenteritis during the first year was significantly less than unity for infants exclusively breast-fed for four months before adjustment (odds ratio = 0.49) and after adjustment for adverse social conditions and seasonality (odds ratio = 0.51). Similarly, univariate analysis and multiple logistic regression analysis of gastroenteritis from birth through four months revealed estimates of the odds ratio that were significantly less than unity for infants exclusively breast-fed for four months (odds ratio = 0.33 and 0.30, respectively). Although a trend of decreasing gastroenteritis with increasing breast feeding was noted across all other feeding groups, the rates of first episodes of gastroenteritis did not significantly differ among all other feeding groups and the bottle-fed. Thus, exclusive breast feeding for four months is associated with reduced risk of early first episodes of gastroenteritis among infants in a less developed community in the United States.