Introduction: Every year millions of children die before reaching their fifth birthday. While the effect of the length of birth interval on child health and survival is well established,there has been little exploration of the links between birth intervals and causes of under-five mortality at either global or regional levels. The purpose of this study is to explore the association between birth intervals and specific causes of death for children under age 5 years in
Afghanistan.

Method: This study is a retrospective analysis of data from the 2010 Afghanistan
Mortality Survey (AMS 2010). The analysis is limited to deaths of children under age 5 years that occurred in the three years before the survey. The dependent variable is the cause-specific mortality rate (CSMR) among children under age 5. The key independent variable is the length of the preceding birth interval, measured as the number of months between the birth of the child under study and the immediately preceding birth to the mother, if any. The analysis used both bivariate and multivariate designs.

Results: After adjusting for socio-demographic characteristics, children with a previous birth interval of less than 18 months have a higher risk of dying from certain causes of death, including sepsis and diarrhea, than children with a previous birth interval of 24-35 months (the reference category). Children with a previous birth interval of at least 60 months also have a higher risk of dying from certain causes, including diarrhea and low birth weight, than children with a previous birth interval of 24-35 months.

Conclusion: The AMS 2010 provides a rich dataset that can be analyzed and used to
generate new information for planners, program managers, and policymakers. This study, which combines data from the survey on causes of death with other covariates of the risk of death of children under age 5, has shown mechanisms by which the length of birth intervals may be related to the risks of dying in childhood. In particular, the length of birth intervals is significantly related to mortality risk from diarrhea, sepsis, and low birth weight. Further analyses in other settings are needed to confirm the generalizability of these conclusions and to establish whether children with non-optimal birth intervals are more likely to contract these
diseases or to have higher case fatalities, or both.