UNOBSERVED HETEROGENEITY AND DETERMINANTS OF INFANT AND CHILD MORTALITY IN RURAL NIGERIA

Abstract

Infant and child mortality remains significantly high among those living in rural Nigeria than their urban counterparts. Besides, previous studies have rarely explored the role of unmeasured variables in the rural-urban differential. This study was conducted to determine which of infant or child mortality is most affected by unobserved heterogeneity. Data from 2013 Nigeria Demographic and Health Survey were analysed to examine the factors that predispose to infant and child mortality in rural Nigeria. Weibull proportional hazard and Weibull frailty models were used. The Hazard ratio (HR) and its 95% confidence interval (CI) were estimated. After controlling for other variables it was found that the risk of infant mortality was lowest among female children (HR=0.83, CI=0.75-0.93) as compared with male children. Hazard of infant mortality was highest among children whose mother's age at child birth was 35 yr or more (HR=1.40, CI=1.13- 1.74) as compared with children whose mother's age was less than 20 yr. Hazard of death was 46 percent (CI=0.54-0.76) and 54 percent (CI=0.40- 0.73) higher at infancy and childhood respectively among birth interval of 35 months or more compared with the first birth. The risk of infant dying was higher among children of other Christians (HR= 1.26, CI=1.03, 1.51) compared with children of Catholic faith, and the risk of death at childhood was highest among other (non Christian) religion (HR=2.46, CI=1.34-4.51). The risk of death was significantly highest in Nor th-east (NE) and North-west (NW) both in infancy and childhood compared with the North-central. At the infancy: NE, (HR= 1.26, (CI=1.05-1.51); NW, (HR=1.40, CI=1.16-1.67) while at childhood: NE, (HR=1.68. Cl=1.26- 2.2 4 ); NW, (HR-1.88, Cl= 1.41-2.51 ). Access to improved toilet facilities reduces the risk of death at infancy compared with unimproved while secondary or higher education reduces the risk of death at childhood. Only maternal age at first birth was significant in the frailty model. Hazard of infant mortality was highest among children whose mother's age at first birth was 35 yr or more (HR=4.45. CI=1.23-16.11) as compared with children whose mother's age was less than 20 yr. The frailty value in infant and child mortality are 51.8 and 56.5 percents respectively, which means that the covariates in infant and child models explained 48.2 percent and 43.5 percent family variation in infant and child deaths in rural Nigeria. Conclusions: Bio-demographic variables are important determinants to infant mortality while socioeconomic variables are important determinants to child mortality. Regional differential also exist in rural Nigeria. Unobserved heterogeneity was found to be significantly associated with high rate of infant and child mortality in rural Nigeria.