Subsequent pregnancy affects morbidity of previous child.

A prospective study of 113 children in rural Bhutan registered their morbidity and weight and their mothers' subsequent pregnancies, monthly for 32 months during the children's first 3 years of life. Children whose mothers had a subsequent birth interval of 18-30 months had an incidence of diarrhoea during the subsequent pregnancy 50% higher than their matched cohort whose mothers did not become pregnant (p = 0.02). The relative risk for diarrhoea calculated from pooled child months was 1.51. Children whose mothers became pregnant also tended to have a higher incidence of skin infections. Children, whose mothers were pregnant when they terminated breastfeeding, experienced an increased incidence of diarrhoea around weaning (p = 0.01). Children weaned at the same age from non-pregnant mothers did not show increased morbidity. This study, for the first time, relates observations of children's morbidity directly in time to the occurrence of the mother's subsequent pregnancy, and provides evidence of a causal relationship between a moderately short subsequent birth interval and a concurrent increase in morbidity for the study child.