In large epidemiologic studies, information on breastfeeding practice is often collected from maternal recall through interviews, but there is concern about the accuracy of the data, especially when mothers are asked to recall their practices from many years earlier. This review examines the validity and reliability of maternal recall of breastfeeding history using 11 studies published between 1966 and 2003 in English with a sample of 10 or more. Validity is the degree to which recall compares with a validation standard or reference, and reliability refers to the degree to which the breastfeeding practices obtained by recall are repeatable over time. The existing studies suggest that maternal recall is a valid and reliable estimate of breastfeeding initiation and duration, especially when the duration of breastfeeding is recalled after a short period (< or = 3 years). Validity and reliability of maternal recall for the age at introduction of food and fluids other than breast milk are less satisfactory. Further and more extensive studies on maternal recall of breastfeeding history and ways to improve such recall are warranted.

Relations between leisure-time physical activity and dietary fat were examined in a population-based probability sample of 29,672 adults in the 1990 Behavioral Risk Factor Surveillance System. Consumption of 13 high-fat food items and participation in physical activities were measured, and fat and activity scores were calculated. Dietary fat and physical activity were strongly and inversely associated. This association was independent of nine other demographic and behavioral risk factors. Etiologic researchers should consider that diet and physical activity can potentially confound each other, and creators of public health messages that target one behavior should consider including the other.

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Two surveys in Upper and Lower rural Egypt allowed an analysis of the seasonality of infant feeding. The first, including 937 children, was conducted during the relatively cool season of low diarrhea incidence in January-April 1978; the second, including 976 children, took place during the hot season of high diarrhea incidence in August-September 1980. Of infants 6-11 mo old, the proportion exclusively breast-feeding was greater in the hot-season survey (40% vs 16% in Lower Egypt, p less than 0.01; 36% vs 22% in Upper Egypt, p less than 0.01). Of children 12-17 mo old, a higher proportion were completely weaned during the hot season in Lower Egypt only (28% vs 14%, p less than 0.01). This difference was explained by an increase in pregnancy rates during the hot season resulting in less breast-feeding. Seasonal variation must be considered in the interpretation of infant-feeding surveys.