Background Nutrition outcomes among young children in Nigeria are among the worse globally. Mother’s limited knowledge about food choices, feeding, and health care seeking practices contributes significantly to negative nutrition outcomes for children in most developing countries. Much less is known about the relationship between mother’s nutrition-related knowledge and child nutritional outcomes in rural Nigeria. This paper investigates therefore: (i) the association of mother’s nutrition-related knowledge with nutrition outcomes of young children living in rural Nigeria, where access to education is limited, and (ii) whether mother’s education has a complementary effect on such knowledge in producing positive child nutrition outcomes in such settings. Methods Using the Demographic and Health Survey data for Nigeria, we employ both descriptive and regression analyses approaches in analyzing the study’s objectives. In particular, we apply ordinary least square (OLS) to investigate the association of mother’s nutrition-related knowledge with child HAZ and WHZ while controlling for maternal, child, household and regional characteristics. An index was constructed for mother’s nutrition-related knowledge using information on dietary practices, disease treatment and prevention, child immunization, and family planning. Results We found that mother’s knowledge is independently and positively associated with HAZ and WHZ scores in young children. Higher levels of mother’s education, typically above primary, have a significant, positive association with child HAZ and WHZ scores. We argue that mother’s knowledge of health and nutrition may substitute for education in reducing undernutrition in young children among populations with limited access to formal education. However, the present level of mother’s education in rural Nigeria appears insufficient to reinforce knowledge in producing better nutrition outcomes for children. Conclusions This study suggests promotion of out-of-school (informal) education, such as adult literacy and numeracy classes where women without formal education can gain health and nutrition knowledge, and practices that could enhance child nutrition outcomes in Nigeria.
The 2013 DHS data employed for this study is the most recent one for Nigeria. The sample was selected using a stratified three-stage cluster design consisting of 904 clusters, with a total of 38,522 households. Sampling errors are computed statistically using appropriate tools and methodologies as provided in the material and methodology document of the 2013 Nigeria Demographic and Health Survey [16]. The children module of the DHS comprises of 31,482 children under five years with their mothers between 15 to 49 years. Children living in rural households are 21,131 (67%), and 5,950 of them are between 6 to 23 years. We only included the youngest child between 6 to 23 months per family, and following deletion of observations with incomplete anthropometric measures, 4,941 mother-child pairs were finally available for analysis. The dataset captures mothers, children, and household information such as socioeconomic characteristics, anthropometric measurements for mother and child, immunization records, health care seeking and feeding practices, water and sanitation, and demographic information among others. Children are being introduced to complementary feeding between 6–23 months, as such, they are the most vulnerable group to undernutrition and consequent growth faltering [3, 37]. Hence, children in this age bracket benefit the most when their mothers have basic knowledge of health and nutritional care. This is a very important, as the consequences of undernutrition, stunting in particular are difficult to reverse in children after the age of two. Height-for-age z-scores (HAZ) and weight-for-height z-score (WHZ) are good indicators of child nutrition and health. Children with HAZ less than two standard deviations below the median measurement for the reference group are said to be stunted or chronically undernourished. While children with WHZ less than two standard deviations below the median measurement for the reference group are regarded as wasted or acutely undernourished [38]. Hence, these two indicators measure whether a child is undernourished (stunted or wasted) or not. It is of policy relevance to investigate separately the factors producing wasting and stunting gauging from these indicators. Our choice of the determinant variables was informed by the literature on the determinants of child nutrition outcomes [39]. We included child and mother characteristics and household characteristics. Child characteristics are sex, age, birthweight and child from multiple birth. Mother characteristics include age at first birth, number of children ever born, mother’s level of education and nutrition and health knowledge of mother (an index computed). Household characteristics are household size; education; age; and an asset-based wealth index, among others. An asset-based wealth index is constructed using a principal components analysis of the NDHS assets data, combining variables on ownership of a radio, bicycle, car, and other items with household dwelling characteristics [40]. This allows households to be ranked by wealth index. We ranked households as poorest tercile wealth index, middle tercile wealth index and wealthiest tercile wealth index. The region dummies where the household belongs, which comprises of the six geopolitical regions of Nigeria. Under this sub-heading, we discuss the computation of mother’s nutrition-related knowledge index, the measurement of mother’s education variable and its interaction with mother’s knowledge. The DHS data contains some important information on dietary practices, disease treatment and prevention, child immunization and family planning. We follow the guidelines for assessing nutrition-related knowledge, attitudes, and practices (KAP) as contained in [41]. Mother’s nutrition-related knowledge was assessed based on five key nutrition and health information as follows: (i) mother’s knowledge of the important of colostrum; (ii) knowledge of continued breastfeeding; (iii) knowledge of diarrhea prevention and treatment using Oral Rehydration Solution (ORS); (iv) knowledge of child immunization; and (v) knowledge of family planning. A detailed description of these variables and their measurement is presented in the result section. Past studies have assessed mother’s nutrition knowledge by either assigning scores to observed knowledge (practice) [42] or scoring mother’s ability to answer “yes” or “no” to a set of questions relating to child health and nutrition [43, 44] or a combination of these [33]. A strong linear relationship between knowledge of young child nutrition and practices has been established in the literature, especially where there are no sociocultural barriers to such practices [45, 46]. We then apply principal component analysis (PCA) as adapted from Filmer and Pritchett [47] to construct the mother’s Nutrition Knowledge Index using the five components highlighted above. Variables for each component are assigned indicator weights that are first standardized; that is, z-scores are calculated and then factor coefficient (factor loading) scores are calculated. More details are shown in S1 File. Since this study is interested in knowing at what level of education is the association of mother’s education most significant with nutrition outcomes, mother’s levels of educational attainment are categorized as follows in the empirical model used: no education, primary education, secondary education, and tertiary education. We further used the interaction between the four educational level dummy variables and mother’s knowledge index to produce four interaction terms. Adding interaction terms to the model helps to better understand the relationship between knowledge and education and the association with outcomes. In other words, to test whether the association of mother’s knowledge with HAZ and WHZ is different at the different levels of mother’s education. For the purpose of nonparametric analysis between mother’s knowledge versus mother’s education on the distribution of HAZ and WHZ scores, we defined mothers with high knowledge as those with above the mean of nutrition-related knowledge in our sample, while mothers with low knowledge are below the mean cut off for nutrition-related knowledge index. For the purpose of interaction model, we categorize mother’s education as no education and with some education. We first adopt a bivariate (nonparametric) analytical approach to understand the relationship between mother’s knowledge versus mother’s education on the distribution of HAZ and WHZ scores using kernel density plots. We also report descriptive statistics that show the means comparisons of variables by maternal education and maternal nutrition-related knowledge. The analytical model employed for this study is a production function similar to the one applied in Rosenzweig and Schultz [48]. The child nutrition outcomes N of child i in household j depend on mother’s nutrition knowledge K, a set of maternal inputs Y, observable individual child’s characteristics I, household characteristics H, and regional characteristics G. This mathematical relationship is specified as: where Nij is the child nutrition outcomes measured by HAZ and WHZ as indicators for stunting and wasting, respectively. Kij is mother’s nutrition knowledge index vector. Yij includes mother’s education, mother’s age at first birth, and the number of children she has borne. Vector Iij includes child’s sex, child’s age and whether child is from multiple birth. The household characteristics vector Hij includes household size and wealth status; while Gij captures the geographic location (zone) where a child grows up (six dummy variables for zones). Ɛij is a vector representing the net effect of all other relevant unobserved factors. This relationship is expressed by the linear function: Where N is child nutrition outcomes and mother’s nutrition knowledge K. Y, I, H and G represent other determinants as specified in Eq (1)). To test whether the association of mother’s knowledge with HAZ and WHZ is different at the different levels of mother’s education, we add interaction terms of knowledge and different levels of mother’s education E. In particular, we estimate the following specification: Mother’s nutrition-related knowledge K is an index constructed based on key nutrition and health information described above. The levels of mother’s education used in the empirical model are no education, primary education, secondary education, and tertiary education.