Knowledge Brief Health, Nutrition and Population Global Practice EARLY CHILDBIRTH AND UNDER-FIVE MORTALITY IN NIGERIA Adenike Onagoruwa and Quentin Wodon June 2017 Child Marriage Series with Education Global Practice KEY MESSAGES:  In Nigeria, about one in eight children dies before the age of five; for children born of mothers younger than 18, the risk is higher.  Controlling for socio-economic and other characteristics, being born of a mother younger than 18 increases the likelihood of dying before the age of five by five percentage points in the baseline model, as compared to otherwise similar children born of older mothers.  Box 1: Brief and Series Primer Early childbirth is associated with health risks for children, including under-five mortality. This could be in part How is early childbirth defined? Early childbirth is defined in because young mothers often come from disadvantaged this brief as a child being born of a mother younger than 18. groups. But the age of the mothers may also play a role. Early childbearing is related to the practice of child marriage. Children of young mothers are at higher risk of Why a series on child marriage? Child marriage has significant negative impacts – not only for girls, but also for a morbidity and under-five mortality. range of development outcomes. Demonstrating these impacts will assist governments and others to make the case for Young mothers often come from disadvantaged socio- intervening to reduce the practice. economic backgrounds and early childbirths are more common in poor areas where prenatal care is limited and What are the topics discussed in the series? The series access to health facilities may be an issue. Girls who looks at the impacts of child marriage on health, population, have children early also tend to be less educated and education, employment, agency, and violence, among other may suffer from lack of agency within the household, outcomes. The welfare, budget, and non-monetary costs of child further reducing access to care. In addition, some girls marriage are estimated. Legal/institutional aspects and options to reduce the practice are also discussed. who give birth early may not yet be ready physiologically to give birth. The risk of obstetric fistula, for example, is What is the question asked in this brief? The question is: higher for young mothers. These various factors lead to How large is the impact of early childbirth on under-five mortality higher risks of under-five mortality for children born of and does it account for a large share of under-five deaths? young mothers. How large is the impact of early childbirth on under-five mortality? Does early childbirth accounts for How is the question answered? Econometric analysis of a large share of under-five deaths? These are the Demographic and Health Survey data is used to estimate the questions asked in this brief for Nigeria. impact of early childbirth on under-five mortality. Page 1 HNPGP Knowledge Brief  Statistically, children from young mothers are five for the children by 4.8 percentage points in comparison to percentage points more likely to die before five. a delivery at 18 to 34 years of age (coefficient statistically significant at the five percent level). The difference in risk The analysis is based on data from the 2013 of under-five mortality between mothers ages 18-34 and Demographic and Health Survey for Nigeria. According to mothers above 35 is not statistically significant. the survey, the under-five mortality remains high with one in eight children dying before the age of five (128 ‰). But Deliveries at a young age increase the likelihood of under- there has also been some progress over time, since the five mortality for the children by 4.8 percentage points in rate observed with the 2003 DHS was 201 ‰ and the rate comparison to a delivery at 18 to 34 years of age. with the 2008 DHS was 157 ‰. (National Population Commission (NPC) [Nigeria] and ICF International. 2014). Marginal effects do not change much when additional controls are used (extended model). There is thus some In this brief we focus on whether all children identified in evidence that in the case of Nigeria, after controlling for a the survey have died or not before reaching five years of wide range of other variables, early childbirth may age, and the factors that affect that outcome. This implies relying on statistics computed in a different way from the contribute to under-five mortality, but prudence remains official under-five mortality rate, but the idea and orders of needed when interpreting the results given the risk of omitted variable bias (box 2). magnitude are similar (to avoid a risk of confusion, we will use below the term “under-five mortality” but not the term Table 2: Impact of Early Childbirth on Under-five “under-five mortality rate”). As shown in table 1, 13.64 Mortality percent of children born of mothers younger than 18 die Age at first marriage Baseline Extended before reaching five years of age. The proportion, which model model we refer to as under-five mortality, is 8.49 percent for Mother younger than 18 0.0482*** 0.0490*** children born of mothers 18 to 34 years of age. The Mother in 18-34 age bracket Reference Reference difference in under-five mortality between the two age Mother older than 35 0.00494 0.00462 groups is statistically significant. For children of older Source: Authors. mothers (35 and older), the under-five mortality is at 9.72 Levels of statistical significance: *** 1%, ** 5%, * 10%. percent. Box 2: Risk of Omitted Variable Bias Table 1: Under-five Mortality by Age of the Mother Age of the mother Under-five Mortality In many countries, early childbirth appears to be positively (‰) correlated with the risk of under-five mortality after controlling for Mother younger than 18 13.64 other factors that may also contribute to mortality. This could Mother in 18-34 age bracket 8.49 indicate a causal effect. However, other variables correlated with Mother older than 35 9.72 both early childbirth and under-five mortality not included in the Source: Authors. analysis could be at the source of the correlation between early childbirth and under-five mortality. Because of the risk of omitted Controlling for other factors, early childbirth variable bias, the results cannot be considered as fully increases the likelihood of under-five mortality. conclusive regarding a causal effect of early childbirth on under- five mortality. The difference in under-five mortality between children of young and older mothers does not necessarily imply a A number of results from the regression analysis not causal effect of the age at delivery, but it does suggest shown in table 2 are worth mentioning. The marginal that early childbirth may contribute to under-five mortality. impact of a mother having a secondary education or To check whether controlling for other factors early better is statistically significant and decreases the childbirth is indeed associated at the margin with higher likelihood of under-five mortality by two percentage points. under-five mortality, regression analysis is used (see the This marginal effect is in comparison to mothers with an annex for details on the methodology). education below the primary level. For primary schooling, the effect is small and not statistically significant. The Table 2 provides key results with baseline and extended impact of wealth on the likelihood of under-five mortality is models. The interpretation of the coefficients is in terms of statistically significant in the third, fourth and fifth wealth marginal impacts in percentage terms. For example, a quintiles. A few other effects are statistically significant, as statistically significant coefficient of 0.05 for a mother discussed in the more detailed study on which the brief is younger than 18 would indicate that children of very based. young mothers have a likelihood of under-five mortality five percentage points higher than children of older The evidence in table 2 suggests that early childbirth mothers, controlling for other characteristics. With the increases the likelihood of under-five mortality. This is a baseline specification, table 2 suggests that deliveries at a direct impact controlling for other independent variables young age increase the likelihood of under-five mortality included in the models. Could early pregnancy and Page 2 HNPGP Knowledge Brief  delivery also have an indirect impact on under-five the risk of under-five mortality is higher by 5.2 percentage mortality through the effect of early pregnancy or delivery points than the risk for children of older mothers. on some of the other variables that are used as controls in the regression? For example, for some of the girls Because only a small share of deliveries are by mothers delivering a baby at a young age, early pregnancy has a younger than 18, only four in 100 children deaths before negative effect on education enrollment and attainment. five can be said to be directly due to early childbirth. Early deliveries, by increasing the number of children that women have, may also contribute to lower labor force Controlling for socio-economic and other characteristics, participation for women and thereby lower household wealth. There could be such effects, but in terms of being born of a mother younger than 18 increases the magnitude, indirect effects are likely to be small in likelihood of under-five mortality for children by five percentage points, as compared to otherwise similar comparison to the direct effects in table 2. children born of older mothers. Given the share of children born of young mothers, nationally for every 100 Early childbirth may also affect under-five mortality children who die before the age of five, four may die indirectly, for example through lower education attainment directly because of an early childbirth. This may appear for mothers, but these effects are likely to be smaller. low, but still represents a large number of children. Simulations suggest that about four in 100 deaths for References children under five are directly due to early childbirth. Bicego, G., & Ahmad, O. (1996). Infant and child mortality, The last step in the analysis of the impact of early Demographic and health surveys comparative studies No. pregnancy and delivery on under-five mortality consists in 20. Calverton (Maryland): Macro International Inc . assessing the potential reduction in under-five mortality National Population Commission (NPC) [Nigeria] and ICF that could arise from eliminating early pregnancies and International. 2014. Nigeria Demographic and Health Survey deliveries. This can be done by predicting (i.e. simulating) 2013. Abuja, Nigeria, and Rockville, Maryland, USA: NPC and the likelihood that children who were born of mothers ICF International. younger than 18 would have remained alive if they had been born of older mothers. In other words, we are Nasrullah, M., Zakar, R., Zakar, M. Z., & Krämer, A. (2014). Girl- considering the direct effects of the age of the mother on child marriage and its association with morbidity and mortality of under-five mortality, shifting in the data deliveries by children under 5 years of age in a nationally-representative young mothers to deliveries at a later age, and observing sample of Pakistan. The Journal of pediatrics,164(3), 639-646. the difference that this makes for under-five mortality Prakash, R., Singh, A., Pathak, P. K., & Parasuraman, S. nationally. (2011). Early marriage, poor reproductive health status of mother and child well-being in India.Journal of family planning The simulations suggest that without early pregnancies and reproductive health care, jfprhc80. and deliveries, the share of children dying before five could decrease by 0.34 percentage point. This essentially Raj, A., Saggurti, N., Winter, M., Labonte, A., Decker, M. R., corresponds to the product of the marginal effect of early Balaiah, D., & Silverman, J. G. (2010). The effect of maternal deliveries on under-five mortality (0.0482 in table 2) times child marriage on morbidity and mortality of children under 5 in the share of children born of mothers younger than 18 India: cross sectional study of a nationally representative (seven percent of children). Given the estimate of under- sample. BMJ, 340. five mortality nationally, four in every 100 children dying Raj, A., & Boehmer, U. (2013). Girl child marriage and its before the age of five can be considered as dying due to association with national rates of HIV, maternal health, and the direct effect of early pregnancies and deliveries on the infant mortality across 97 countries.Violence against likelihood of under-five mortality. This may appear women, 19(4), 536-551. relatively low in comparison to the total number of children who die, but still represents a large number of children. Raj, A., McDougal, L., & Rusch, M. L. (2014). Effects of young maternal age and short interpregnancy interval on infant Conclusion mortality in South Asia. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics, 124(1), 86. Early pregnancy and delivery may contribute to the risk of under-five mortality for children, directly, or indirectly. This brief has provided estimates of the direct impact of early childbirth on under-five mortality in Nigeria using the latest DHS survey. About one in eight children under the age of five die; but for children born of mothers younger than 18, Page 3 HNPGP Knowledge Brief  Annex: Methodological Note It is worth noting that the specifications used for modeling the correlates of under-five mortality are more parsimonious in terms There is an existing literature on the relationship between early of the independent variables included than the specifications pregnancy (as well as child marriage) and the risks of infant, used in a separate analysis by the authors for malnutrition using child, and under-five mortality. Much of the literature focuses on stunting as the main measure of interest. In principle, given that South Asia (e.g., Bicego, 1996; Adhikari, 2003; Raj, 2010; Raj et malnutrition is a key factor leading to premature death for al., 2013; Raj and Boehmer, 2013; Prakash et al., 2011; children, one could argue that all correlates of under-five Nasrullah et al., 2014). The results suggest that children born of malnutrition should also be used as correlates of under-five young mothers are indeed at higher risk of under-five mortality. mortality. The issue however is that the rate of under-five mortality in countries is much smaller than the rate of stunting. Statistics comparing under-five mortality according to the age of The models used tend to perform less well when very few of the the mother may hint at the relationship between the two. But for observations take on a positive value for the dependent variable assessing marginal impacts, regression analysis is needed. Part (i.e., dying before the age of five). In addition, when many more of the literature relies on survival models, which provide variables are used, there is also a much higher risk of perfect information on how long children survive given their correlation (prediction) between some of the variables and the characteristics. The models are censored, in that if a child has dependent variable, in which case the independent variable will survived beyond five years of age, s/he is considered as having be dropped from the model as well as the observations for which avoided under-five mortality. One may also rely on simpler logit the outcome was perfectly predicted. This calls for being or probit models to analyze under-five mortality. In this case, the somewhat parsimonious in the specifications. focus is on whether the child has survived, or not, as opposed to how long the child has survived. Given the focus in this brief on In addition to what is often done in the literature, this brief also the contribution of early pregnancies and deliveries to under-five assesses the potential reduction in under-five mortality that mortality, results from the probit regressions will be presented, could arise from eliminating early pregnancies and deliveries, or, as they provide a simple way to provide those estimates. said differently, the share of deaths for children under five that can be attributed to early childbirth according to the results. Different specifications are estimated to assess the robustness Finally, in term of interpretation, it is important to mention the of the results to changes in the econometric models. Overall, the risk of omitted variables bias, as noted in Box 3 of the brief. main results are robust to different specifications. For the baseline model, the independent variables are: (1) the age of the mother at the time of delivery by categories; (2) the child’s This brief was produced by a World Bank team as part of the Economic gender; (3) whether the child had siblings born at the same time Impacts of Child Marriage study. The synthesis report under the study (multiple birth); (4) the birth order of the child and the child’s birth was produced jointly with the International Center for Research on weight by categories; (5) the length of time between the child’s Women. The study benefitted from support from the Bill & Melinda Gates birth and a previous birth for the mother; (6) whether the delivery Foundation, the Children’s Investment Fund Foundation, and the Global took place in a health facility; (7) the location of the child by Partnership for Education. Comments from colleagues and peer reviewers are gratefully acknowledged. The opinions expressed in this region and by urban-rural category; (8) the education of the brief are those of the authors only and need not reflect the views of the mother; (9) whether the household has access to an improved World Bank, its Executive Directors, of the countries they represent. water source and improved sanitation; (10) the wealth quintile of the household; (11) whether the household practices polygyny; and finally (12) indicators of decision-making power for the mother in the household. The Health, Nutrition and Population Knowledge Briefs of the World Bank are a quick reference on the essentials of specific HNP-related topics summarizing new findings and information. These may highlight an issue and key interventions proven to be effective in improving health, or disseminate new findings and lessons learned from the regions. For more information on this topic, go to: www.worldbank.org/health. Page 4