Explaining the Rapid Increase in Nigeria’s Sex Ratio at Birth: Factors and Implications

Amadu J. Kaba


This paper examines the rapid increase in Nigeria’s sex ratio at birth from 1.03 boys born for every 1 girl born in each year from 1996-2008 to 1.06 in each year from 2009-2014, second only to Tunisia in Africa at 1.07. The average sex ratio at birth in the world in 2014 was 1.07. In most Black African nations or Black majority nations, it is 1.03 or less. Among the factors presented for this development are: historical fluctuations of sex ratio at birth; geography and ethnicity; male preference/chasing a son; Age of parents; high death rates of male infants and males in general; and wealth/socioeconomic status. Among the potential implications are: young and poor men in Nigeria may not be able to find brides and form families due to a potential shortage of females; emigration of young and poor Nigerian men to West (Africa) and elsewhere to seek brides and form families; immigration of marriage age women from West (Africa) and around the world to Nigeria to seek husbands; and low contraceptive use and high fertility rates in Nigeria. (Afr J Reprod Health 2015; 19[2]: 17-33).

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CIA World Fact book, 2014. also see notes 2-5. 2. Citro, B., Gilson, J., Kalantry, S. & Stricker, K.

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Replacing Myths with Facts: Sex-Selective Abortion Laws in the United States. International Human Rights Clinic, University of Chicago Law School. 2014, May: 8-9. http://napawf.org/wpcontent/uploads/2014/06/Replacing-Myths-withFacts-final.pdf. 3. Coney, N. S. & Mackey, W.C. The Woman as Final Arbiter: A Case for the Facultative Character of the Human Sex Ratio, The Journal of Sex Research, 1998: 35 (2):169-175. 4. Dama, M. S. Sex Ratio at Birth and Mortality Rates are Negatively Related in Humans. PLoS ONE, 2011: 6 (8): e23792 (6 pages). 5. Seth, S. Skewed Sex Ratio at Birth in India. Journal of Biosocial Science, 2010: 42 (1): 83-97. 6. Azeez, M.A., Akinboro, A. & Bakare, A.A. Human Sex Ratio at Birth in South West Nigeria. Indian Journal of Human Genetics, 2007: 13 (2): 59-64. 7. Kaba, A. J. Sex Ratio at Birth and Racial Differences: Why Do Black Women Give Birth to More Females Than Non-Black Women? African Journal of Reproductive Health. 2008: 12 (3): 141-142. 8. Davis, D., Webster, P., Stainthorpe, H., Chilton, J., Jones, L. & Doi, R. Declines in Sex Ratio at Birth and Fetal Deaths in Japan, and in U.S. Whites and But Not African Americans. Environment Health Perspectives, 2007: 15, (6): 941-946. 9. Egwuatu, V.E. The Sex Ratio of Igbo Births. International Journal of Gynaecology and Obstetrics, 1984: 22 (5): 399-402. 10. Garenne, M. Sex Ratio at Birth in African Populations: A Review of Survey Data. Human Biology, 2002: 74 (6): 889-900. 11. Garenne, M. Poisson Variations of the Sex Ratio at Birth in African Demographic Survey, Human Biology, 2008: 80 (5): 473-482. 12. Udjo, E.O. Fertility Levels among Nigeria’s Kanuri. Genus, 1991: 47 (1-2): 163. 13. Ayeni, O. Sex Ratio of Live Births in South-Western Nigeria. Annals of Human Biology, 1975: 2 (2): 137-141. 14. Navara, K. J. Humans at Tropical Latitudes Produce More Females. Biology Letters, 2009: 5 (4): 524-527. 15. Rehan, N.E. Sex Ratio of Live-born Hausa Infants. British Journal of Obstetrics and Gynaecology, 1982: 89 (2): 136-141. 16. Adebowale, S.A., Yusuf, O.B. & Palmuleni, E.A. Child’s Gender Preference: What is the Regional Situation among Women in Nigeria. Gender and Society, 2014: 12 (3): 5868- 5869. 17. Firth, R., Mlay, P., Walker, R., and Silt, P. R. Pregnant Women’s Beliefs, Expectations & Experiences of Antenatal Ultrasound in Northern Tanzania. African Journal of Reproductive Health, 2011: 15 (2): 96. 18. Milazzo, A. Son Preference, Fertility and Family Structure: Evidence from Reproductive Behavior among Nigerian Women. Policy Research Working Paper 6869. The World Bank Development Research Group. 2014, May: 2-4.http://econ. worldbank.org/external/default/main?pagePK=

&piPK=64165421&theSitePK=469382& menuPK=64166093&entityID=000158349_201405 19144236. 19. Ohagwu, C.C., Eze, C.U., Eze, J.C., Odo, M.C., Abu, P.O. & Ohagwu, C.I. Perception of Male Gender Preference among Pregnant Igbo Women. Annals of Medical and Health Sciences Research, 2014: 4 (2): 173-174. 20. Garg, S. & Nath, A. Female Feticide in India: Issues and Concerns Journal of Postgraduate Medicine, 2008: 54 (4): 276-279. 21. Melhado, L. Sex-Selective Abortions During Past Three Decades May Explain Absence of Millions of Girls in India. International Perspectives on Sexual and Reproductive Health, 2011: 37 (3): 162-163. 22. Sen, A. Missing Women – Revisited. British Medical Journal, 2003: 32: 1297-1298. 23. Aderibigbe, S. A., Araoye, M. O., Akande, T. M., Musa, O. I., Monehin, J. O. & Babatunde, O. A. Teenage Pregnancy and Prevalence of Abortion among Inschool Adolescents in North Central, Nigeria. Asian Social Science, 2011: 7 (1): 122-127. 24. Adeyemi, A.B., Irinoye, O.O., Oladimeji, B.Y., Fatusi, A.O., Fatoye, F.O., Mosaku, S.K. & Ola, Bola A. Preparedness for Management and Prevention of Violence Against Women by Nigerian Health Professionals. Journal of Family Violence, 2008: 23 (8): 719- 725. 25. Awopetu, G. R. & Fasanmi, S. S. Psychosocial Factors Influencing Attitude Towards Abortion among Undergraduates in Nigeria. Gender & Behavior, 2011: 9 (2): 4262-4275. 26. Maaji, S.M., Ekele, B.A., Bello, S.O. & Morhason-Bello, I.O. Do Women Want Disclosure of Fetal Gender During Prenatal Ultrasound Scan? Annals of African Medicine, 2010: 9, (1):12. 27. Sedgh, G., Bankole, A., Oye-Adeniran, B., Adewole, I. F., Singh, S. & Hussain, R. Unwanted Pregnancy and Associated Factors Among Nigerian Women. International Family Planning Perspectives, 2006: 32 (4): 175-184. 28. Anonymous. Bring Back the Girls: Fertility and Son- Preference in Nigeria. The Economist, 2014, July 19: 44. 29. Fayemi, M. M., Oduola, O. L., Ogbuji, Q. C., Osinowo, K. A., Oyewo, A. E. & Osiberu, O. M. The Knowledge of Eemergency Contraception and Dispensing Practices of Patent Medicine Vendors in South West Nigeria. Journal of Public Health Policy, 2010: 31 (3): 281-282. 30. Lauro, D. Abortion and Contraceptive Use in Sub-Saharan Africa: How Women Plan Their Families. African Journal of Reproductive Health, 2011: 15 (1):13-23. 31. Bendavid, E., Avila, P. & Miller, G. United States Aid Policy and Induced Abortion in Sub-Saharan Africa. Bulletin of the World Health Organization, 2011: 89 (12): 873-880C. 32. Omideyi, A. K., Akinyemi, A. I., Aina, O. I., Adeyemi, A. B., Fadeyibi, O. A., Bamiwuye, O. S., Akinbami, C. A. & Anazodo, A. Contraceptive Practice,

Kaba, A.J. Explaining the Rapid Increase

African Journal of Reproductive Health June 2015; 19 (2): 32

Unwanted Pregnancies and Induced Abortion in Southwest Nigeria. Global Public Health, 2011: 6 (S1):S52-S72; Mitsunaga, T.M., Larsen, U.M., & Okonofua, F. Risk Factors for Complications of Induced Abortions in Nigeria. Journal of Women’s Health, 2005: 14 (6): 519-521. 33. Wadley, R.L & Martin, J. F. On Secondary Sex Ratio and Coital Frequency with an Iban Case. Current Anthropology, 1997: 38 (1): 79-81. 34. Ugoji, F.N. Parental Marital Status and Peer Influence as Corelates of Teenage Pregnancy among Female Teens in South-South Nigeria. Gender & Behaviour, 2011: 9 (2): 4125-4138. 35. Oyefara, J. L. Determinants of Adolescent Fertility in Contemporary Yoruba Society: A Multivariate Analysis. Gender & Behaviour, 2011: 9 (2): 39794004. 36. Walker, J.A. Early Marriage in Africa – Trends, Harmful Effects and Interventions. African Journal of Reproductive Health, 2012; 16 (2): 231-240. 37. Compiled and computed based on data in the 2008 and 2009 CIA World Factbooks. 38. Country Rank, 2013. International Programs. U.S. Census Bureau. Retrieved on January 2, 2015 from: http://www.census.gov/population/international/dat a/countryrank/rank.php. 39. Schneider, F. & Enste, D. Shadow Economies: Size, Causes, and Consequences. Journal of Economic Literature, 2000: 38 (1): 80. 40. Kaba, A. J. Educational Attainment, Income Levels and Africans in the United States: The Paradox of Nigerian Immigrants. West Africa Review, 2007: (11): 3. 41. Parker, G. Nigeria becomes Africa's No. 1 economy, overtaking South Africa. The Christian Science Monitor, 2014, April 8: 7. 42. Kay, C. Nigerian Millionaires to Soar 47% in Next Four Years, Study Says. Bloomberg News, 2014, March 4. Retrieved on January 2, 2015 from: http://www.bloomberg.com/news/2014-03-04/ nigerian-millionaires-to-soar-47-in-next-four-yearsstudy-says.html. 43. The Africa 2014 Wealth Report. Research and Markets. 2014. Retrieved on January 1, 2015 from: http://www.researchandmarkets.com/reports/30221 88/the-africa-2014-wealth-r eport#pos-0). 44. Nigerian millionaires forecast to soar. Business Report (South Africa). 2014, March 4. Retrieved on January 2, 2015 from: http://www.iol.co.za/ business/international/nigerian-millionaires-forecast -to-soar 1.1656197#.VKcUcTEo59A. 45. Dolan, K. A. Nigerian Tycoons Lead Africa’s 50 Richest to Gains in 2014. Forbes Magazine, 2014, November 19. Retrieved on January 3, 2015 from: http://www.forbes.com/sites/kerryadolan/2014/11/ 19/africas-50-richest-2014-worth-a-combined-111billion-up-nearly-7-percent-from-a-year-ago/ 46. Africa’s 50 Richest. Forbes Magazine. 2014. Retrieved on January 2, 2015 from:http://www.forbes.com/africa- billionaires/list/#tab:overall.

Nsehe, M. The Black Billionaires 2014. Forbes Magazine, 2014, March 4. Retrieved on January 2, 2015 from:http: //www.forbes.com/sites/ mfonobongnsehe/2014/03/04/the-black-billionaires2014/2/. 48. d’Albis, H. & de la Croix, D. Missing Daughters, Missing Brides. Economics Letters, 2012: 116 (3): 358-360. 49. Attané, I. The Demographic Impact of a Female deficit in China, 2000-2050. Population & Development Review, 2006: 32 (4): 755-770. 50. Hesketh, T. Too Many Males in China: The Causes and Consequences. Significance, 2009: 6 (1): 9-13. 51. Westley, S. B. & Choe, M. K. How Does Son Preference Affect Populations in Asia? Asia Pacific Issues, 2007: 84: 1-12. 52. Yang, X., Attané, I., Li, S. & Zhang, Q. Masturbation as a Compensation for Partnered- Sex among Enforced Male Bachelor’s in Rural China – Findings from a Survey Conducted in the Context of a Deficit of Females. Journal of Men’s Health, 2012: 9 (4): 220229. 53. Zhou, X. D., Wang, X. L. & Hesketh, T. The Very High Sex Ratio in Rural China: Impact on the Psychosocial Wellbeing of Unmarried Men. Social Science & Medicine, 2011: 73 (9): 1422-1427. 54. Smith, D. J. ‘Man No Be Wood’: Gender and Extramarital Sex in Contemporary Southeastern Nigeria. Ahfad Journal, 2002: 19 (2): 4-23. 55. Okonkwo, A. Gender and Sexual Risk-Taking among Selected Nigerian University Students. Sexuality & Culture, 2010: 14 (4): 270-305. 56. Smith, D. J. Promiscuous Girls, Good Wives, and Cheating Husbands: Gender Inequality, Transitions to Marriage, and Infidelity in Southeastern Nigeria. Anthropological Quarterly, 2010: 83 (1): 123-152. 57. Chin-Quee, D., L’Engle, K., Otterness, C., Mercer, S. & Chen, M. Repeat Use of Emergency Contraceptive Pills in Urban Kenya and Nigeria. International Perspectives on Sexual and Reproductive Health, 2014: 40 (3): 127-134. 58. Doskoch, P. Contraceptive Use is Rising Faster in Eastern than Western Africa. International Perspectives on Sexual and Reproductive Health, 2011:37(1): 49-50. 59. Ibisomi, L. Is Age Difference Between Partners Associated with Contraceptive Use among Married Couples in Nigeria? International Perspectives on Sexual and Reproductive Health, 2014:40 (1):39-45. 60. Akinyemi, AL., Aransiola, J.O., Banjo, O., Bamiwuye, O., Fadeyibi, O. & Adewuyi, A. “Influence of Independent and Proximate Variables in Condom Use in Selected States in Nigeria,”African Journal of Reproductive Health, 2010: 13 (4): 53-62. 61. Antai, D. Regional Inequalities in Under-5 Mortality in Nigeria: A Population-Based Analysis of Individual- and Community-Level Determinants. Population Health Metrics, 2011: 9 (1): 6-15. 62. Antai, D., Ghilagaber, G., Wedrén, S., Macassa, G. &

Kaba, A.J. Explaining the Rapid Increase

African Journal of Reproductive Health June 2015; 19 (2): 33

Moradi, T. Inequalities in Under-Five Mortality in Nigeria: Differentials by Religious Affiliation of the Mother. Journal of Religion and Health, 2009: 48 (3): 290-304. 63. Ayotunde, T., Mary, O., Melvin, A. O. & Fanniyi, F. F. Maternal Age at Birth and Under-5 Mortality in Nigeria. East African Journal of Public Health, 2009: 6 (1): 11-14. 64. Idowu, A. E., Osinaike, M. O. & Ajayi, M. P. Maternal Health Challenges and Prospectus for National Development: A Case-Study of Badagry Local Government, Lagos State. Gender & Behavior, 2011: 9 (2): 4224-4246. 65. Okonofua, F. E. Maternal Mortality Prevention in Africa – Need to Focus on Access and Quality of Care. African Journal of Reproductive Health, 2008: 12 (3): 9-12. 66. Okonofua, F. E. Reducing Maternal Mortality in Nigeria: An Approach through Policy Research and Capacity Building. African Journal of Reproductive Health, 2010: 14 (3): 9-10. 67. Izugbara, C. O. & Ezeh, A. C. Women and High Fertility in Islamic Northern Nigeria. Studies in Family Planning, 2010: 41 (3): 193-204. 68. Okore, A.O. Rural-Urban Fertility Differentials in Southern Nigeria: An Assessment of Some Available Evidence Population Studies, 1980: 34 (1): 171-179. 69. There are a number of organizations that provide access to the CIA World Factbook, which they have archived going back decades. The data were compiled from two non-profit organizations: Project Gutenberg (http://www.gutenberg.org/wiki/Main_Page) and theodora.com. A careful research shows that the sex ratio at birth data was first provided by the World Factbook in 1996.(http://www.theodora.com/ wfbcurrent/nigeria/index.html)(https://www.gutenb erg. org/wiki/CIA_World_Factbooks_(Bookshelf). 70. Emelumadu, O.F., Ezeama, N.N., Ifeadike, C.O., Ubajaka, C.F., Adogu, P.O.U., Umeh, U., Nwamoh, U.S., Ukegbu, A.U., & Onyeonoro, U.U. Parents’

Perceptions of Timing of Initiation of Sexuality Discussion with Adolescents in Anambra State, South Eastern Nigeria. Journal of Pediatric and Adolescent Gynecology, 2014: 27 (5): 294-300. 71. Gayawan, E., & Adebayo, S.B. A Bayesian Semiparametric Multilevel Survival Modelling of Age at First Birth in Nigeria. Demographic Research, 2013: 20 (45): 1339-1366; Oyefara, J.L. Age at First Birth and Social Dimensions of Under5 Child Mortality in Yoruba Society: The Case of Osun State, Nigeria. Ife PsychologIA, 2015: 23 (1): 184-196. 72. Adebimpe, W. O. A Survey of Marriage Pattern as Determinants of Fertility Among Women in Southwestern Nigeria. TAF Preventive Medicine Bulletin, 2013: 12 (2): 143-150. 73. Olatoregun, O., Fagbamigbe, A.F., Akinyemi, O.J., Yusuf, O.B., & Bamgboye, E.A. A Comparative Analysis of Fertility Differentials in Ghana and Nigeria. African Journal of Reproductive Health, 2014: 18 (3): 36-47. 74. Oladeji, D. & Ariyo, A.M. Socio-economic Factors Influencing Mate Selection among Adolescents of Reproductive Age in Nigeria. Gender & Behavior, 2014: 12 (1): 6145- 6155. 75. Ogunlesi, T. Have over 13,000 people been killed in Nigeria’s insurgency? The claim is broadly correct. Africa Check. 2014, October 14. Retrieved on May 15, 2015, from: http://africacheck.org/ reports/have13000-people-been-killed-in-nigerias-insurgencythe-claim-is-broadly-correct/. 76. Campbell, J. “Nigeria Security Tracker: Mapping Violence in Nigeria.” Council on Foreign Relations. 2015, May 16. Retrieved on Saturday May 16, 2015 from:http://www.cfr.org/Nigeria/nigeria-securitytracker/p29483. 77. Olusanya, B., Inem, V.A., & Abosede, O.A. Infants Delivered in Maternity Homes Run by Traditional Birth Attendants in Urban Nigeria: A CommunityBased Study. Health Care for Women. International, 2011: 32 (6): 480.


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