Regional and socioeconomic inequalities in infant mortality in Nigeria
This study measures socioeconomic inequalities in infant mortality at the national and regional level in Nigeria based on secondary data from the 2003, 2008 and 2013 Nigeria demographic and health survey. Inequalities were assessed among groups defined by wealth, mother’s level of education and mother’s age using both simple range measures (Rate ratio and Rate difference) and more complex measures (Slope Index of Inequality, Concentration Index and Population Attributable Fraction). All measures identified significant inequalities in infant mortality amongst socioeconomic groups over space and time in Nigeria. Results showed that inequalities mostly favoured better-off groups. However, both relative and absolute inequalities between groups increased in some areas but generally narrowed to some degree or remained the same over time in most areas. Findings clearly show that a significant proportion of infant deaths could have been avoided in Nigeria over the 15 year period examined if socioeconomic inequalities in infant mortality rates had been eliminated/reduced by appropriate policy measures.
KeywordsInfant mortality rates Socioeconomic inequalities Relative inequalities Absolute inequalities Nigeria
The Author is grateful to ICF Macro, Calverton, USA for providing access to the 2003, 2008 and 2013 demographic and health survey data for Nigeria.
Compliance with ethical standards
Conflict of interest
There are no conflicts of interest. No funding was received for this research.
Ethical approval was granted for the secondary analysis of existing demographic and health survey data after the removal of all identifying information of the respondents by the Institutional Review Board (IRB) of the ICF Macro at Calverton, USA in conjunction with the National Health Research Ethics Committee (NHREC) of the Federal Ministry of Health, Abuja, Nigeria.
- Adebayo, S. B., Fahrmeir, L., & Klasen, S. (2004). Analyzing infant mortality with geoadditive categorical regression models: A case study of Nigeria. Economics and Human Biology, 2(2), 229–244.Google Scholar
- Adebowale, A. S., & Udjo, E. (2016). Maternal health care services access index and infant survival in Nigeria. Ethiopian Journal of Health Science, 26(2), 131–144.Google Scholar
- Adekanmbi, V. T., Kandala, N., Stranges, S., & Uthman, O. A. (2015). Contextual socioeconomic factors associated with childhood mortality in Nigeria: A multilevel analysis. Journal of Epidemiology and Community Health, 69(11), 1102–1108.Google Scholar
- Adetunji, J. A. (1995). Infant mortality and mother’s education in Ondo state Nigeria. Social Science and Medicine, 40(2), 253–263.Google Scholar
- Ahonsi, B. A. (1995). Age variations in the proximate determinants of child mortality in Southwest Nigeria. Journal of BioSocial Sciences, 27(1), 19–30.Google Scholar
- Aigbe, G. O., & Zannu, A. E. (2012). Differentials in infant and child mortality rates in Nigeria: Evidence from the six geopolitical zones. International Journal of Humanities and Social Sciences, 2(6), 206–214.Google Scholar
- Alagi, M.A. and Dairo, D.M. (2014). Socioeconomic determinants of inequalities in under-5 mortality in Nigeria: analysis of NDHS. 20th IEA world congress of epidemiology, 17–21 August, 2014, Anchorage, Alaska USA.Google Scholar
- Ayenigbara, G. O., & Olorunmaye, V. B. (2012). Investigating the causes of infant mortality in Akoko South West Local Government Area, Ondo, Nigeria. Public Health Research, 2(6), 180–184.Google Scholar
- Bado, A. R., & Susuman, A. S. (2016). Women’s education and health inequalities in under-five mortality in selected Sub-Saharan African countries, 1990–2015. PLoS ONE, 11(7), e0159186.Google Scholar
- Caldwell, J. C. (1979). Education as a factor in mortality decline: An examination of Nigerian data. Population Studies, 33(3), 395–413.Google Scholar
- Castro, M.C. and Simoes, C.C.S. (2009). Spatio-temporal trends of infant mortality in Brazil. Paper presented at the xxvi international population conference, Marrakech, Morocco, September, 2009.Google Scholar
- Congdon, P. (2001). Quantifying and explaining changes in geographical inequality of infant mortality in England and Wales since the 1890s. International Journal of Population Geography, 7(1), 35–51.Google Scholar
- Fagbamigbe, A. F., & Alabi, O. (2014). Differentials and correlates of infant mortality in Nigeria: A comparative survival analysis between Northeast and Southwest Nigeria. Internaional Journal of Tropical Disease, 4(8), 869–886.Google Scholar
- Finlay, J. E., Norton, M. K., & Meiji-Guevara, I. (2017). Adolescent fertility and child health: The interaction of maternal age, parity and birth intervals in determining child health outcomes. International Journal of Child Health and Nutrition, 6(1), 16–33.Google Scholar
- Iyun, B. F. (1992). Women’s status and childhood mortality in two contrasting areas in Southwestern Nigeria: A preliminary analysis. GeoJournal, 26(1), 43–52.Google Scholar
- Jacdonmi, I., Suhainizam, M. S., & Jacdonmi, G. R. (2016). Breastfeeding, a child survival strategy against infant mortality in Nigeria. Current Science, 110(7), 1282–1287.Google Scholar
- Lee, H., Van Do, D., Choi, S., Trinh, O. H., & Gia To, K. (2016). Trends and determinants of infant and under-five childhood mortality in Vietnam, 1986–2011. Global health Action, 9(1). https://doi.org/10.3402/gha.V9.29312.
- Low, A., & Low, A. (2004). Measuring the gap: Quantifying and comparing local health inequalities. Journal of Public Health, 26(4), 388–395.Google Scholar
- Marmot, M. (2005). Social determinants of health inequalities. The Lancet, 365(9464), 1099–1104.Google Scholar
- Morakinyo, O. M., & Fagbamigbe, A. F. (2017). Neonatal, infant and under-five mortalities in Nigeria: An examination of trends and drivers (2003–2013). PLoS ONE, 12(8), e0182990.Google Scholar
- Mosley, W.H. and Chen, L.C. (1984). An analytical framework for the study of child survival in developing countries. Bulletin of the WHO, 2003: 81(2) (extracted from the Population and Development Review 10 Suppl: 25-45).Google Scholar
- Mujica, O. J., Vasquez, E., Duarte, E. C., Cortez-Escalante, J. J., Molina, J., & Barbosa da Silva Junior, J. (2014). Socioeconomic inequalities and mortality trends in BRICS, 1990–2010. Bulletin of the WHO, 92(6), 405–412.Google Scholar
- Nwaokoro, J. C., Ibe Sally, N. O., Ihenachor, C. A., Emerole, C. O., Nwufo, R. C., Ebiriekwe, S. C., et al. (2015). Risk factors associated with infant mortality in Owerri metropolis, Imo state, Southeastern Nigeria. Science Journal of Public Health, 3(5–1), 64–71.Google Scholar
- Quentin, W., Abosede, O., Aka, J., Akweongo, P., Dinard, K., Ezeh, A., et al. (2014). Inequalities in child mortality in ten major African cities. BMC Medicine, 12(95). https://doi.org/10.1186/1741-7015-12-95.
- Rutherford, M. E., Mulholland, K., & Hill, P. C. (2010). How access to health care relates to under-five mortality in Sub-Saharan Africa: Systematic review. Journal of Medicine and International Health, 15(5), 508–519.Google Scholar
- Sartorius, K. D., & Sartorius, K. (2014). Global infant mortality trends and attributable determinants – an ecological study using data from 192 countries for the period 1990–2011. Population Health Metrics, 12(29). https://doi.org/10.1186/s12963-014-0029-6.
- Schneider, M. C., Castillo-Salgado, S., Bacallo, J., Loyola, E., Mujica, O. J., Vidaurre, M., et al. (2005). Methods for measuring health inequalities II. Epidemiological Bulletin/PAHO, 26(1), 5–10.Google Scholar
- Schneider, M. C., Castillo-Salgado, C., Loyola-Elizondo, E., Bacallao, J., Mujica, O. J., Vidaurre, M., et al. (2002). Trends in infant mortality inequalities in the Americas: 1955–1995. Journal of Epidemiology and Community Health, 56(7), 538–541.Google Scholar
- Shen, C. E., & Williamson, J. B. (2001). Accounting for cross-national differences in infant mortality decline (1965–1991) among less developed countries: Effects of women’s status, economic dependency, and state strength. Social Indicators Research, 53(3), 257–288.Google Scholar
- UN-IGME. (2017). Levels and trends in child mortality. Estimates developed by the United Nations Inter-agency group for child mortality estimation (UNICEF, WHO, World Bank and the United Nations Population Division).Google Scholar
- Victora, C. G., Wagstaff, A., Schellenberg, J. A., Gwatkin, D., Claeson, M., & Habicht, J. (2003). Applying an equity lens to child health and mortality: More of the same is not enough. The Lancet, 362(9379), 233–341.Google Scholar
- Wagstaff, A. (2000). Socioeconomic inequalities in child mortality: Comparisons across 9 developing countries. Bulletin of the WHO, 78(1), 19–29.Google Scholar
- Wagstaff, A., Pierella, P., & Doorslaer, E. (1991). On the measurement of inequalities in health. Social Science and Medicine, 33(5), 545–557.Google Scholar
- WHO. (2008). Closing the gap in a generation: health equity through action on the social determinants of health. Geneva: Final Report of the Commission on Social Determinants of Health.Google Scholar