Diarrhea and growth in children under 18 months of age in Rio de Janeiro

159 children under 18 months old in a periurban area of Rio de Janeiro were prospectively studied between January and September 1985 to determine the effects of diarrhea on their weight and height. The mothers were interviewed in their homes each week about diarrheal episodes in their infants. Clinical characteristics of the diarrhea use of health services and the mothers attitudes were noted. Beginning in January 1985 the weight and length of study participants were measured each month. A multiple regression model was used to determine whether a relationship existed between the prevalence of days with diarrhea and the increase of weight and length. 69% of the 159 children were followed for the duration of the study which was 8 months for a 1st cohort of 68 infants and 4-6 months for a 2nd cohort of 91 children. Diarrhea was reported during 8.4% of observation days. The prevalence was lower among younger children and began to increase at the 6th months of life to reach a maximum at 10-12 months. The percentage of days with diarrhea was 5.51 for infants 0-3 months old 6.85 for those 4-6 months old 9.33 for those 7-9 months 9.38 for those 10-12 months and 9.15 for those 13-18 months old. 374 episodes of diarrhea were identified from January to September 1985 and 81.0% of the children had at least 1 diarrheal episode. About 70% of diarrheal episodes lasted 7 days or less and 8.3% lasted 14-35 days. The 159 study children were weighed 963 times and measured 951 times at an average interval of 32 days. 12% of the sample weighed less than 2500 g at birth. A comparison of the distribution of the standardized percentiles of weight increase in the study children with reference patterns indicated that the percentage of children with a weight increase under the 10th percentile was 46% higher than expected. A slight decline in the proportion under the 10th percentile was noted as age increased. A similar analysis for increase in length standardized by month showed that the proportion of children with an increase under the 10th percentile was 60% greater than expected. The prevalence of diarrhea showed a very significant inverse relation with the increase in weight standardized by month. In the study children diarrhea reduced weight increase on average by 13.4 g per day and height increase by .132 mm per day.