High-risk fertility behavior is a major public health concern in low and middle-income countries including Ethiopia. Some studies show that the relationship between high-risk fertility behavior and child mortality has analyzed each fertility behavior individually. Yet, there are limited studies that have analyzed outcomes associated with the joint impact of high-risk fertility behaviors. Therefore, the objective of this study was to examine the individual and combined influence of high-risk fertility behavior on under-five mortalities in Ethiopia.

Data from the 2016 Ethiopian Demographic and Health Survey were used analyzed. A total of 10,773 mothers who gave live births were included in the final analysis. Both descriptive and bivariate and multivariate logistic regression analyses were performed using STATA V.14.

Overall, 62.1%, 24.0%, and 2.3% of women experienced at least one, two, and three high-risk fertility behaviors, respectively. In the multivariable analysis, under-five mortality was significantly associated with a combination of two or more maternal high-risk fertility behaviors. The odds of under-five mortality among children of women who were engaged in a combination of two high-risk fertility behaviors (AOR = 2.17, 95%CI: 1.52–3.08) and three high-risk fertility behaviors (AOR = 3.69, 95%CI:1.80, 7.55) was higher compared to children of women who have not engaged any high-risk fertility behaviors.

This study revealed that a single high-risk fertility behavior was not associated with under-five mortality, yet the presence of two or more maternal high-risk fertility behaviors was an important factor that increased the likelihood of under-five child death. Thus, special emphasis should be given to children of women who engage in a combination of high-risk fertility behaviors. Furthermore, more emphasis should be placed on increasing access to family planning services and raising awareness about high-risk reproductive behaviors among Ethiopian women.