Skip to main content


  • Victor Grech (a1)

Many factors influence the male:female birth ratio (number of male births divided by total births, M/T). Studies have suggested that this ratio may be positively correlated with the education levels of mothers. This study assessed the effect of maternal education on M/T in the US population overall and by racial group. Number of live births by sex of the child, maternal educational level reached and race were obtained from the Centres for Disease Control (CDC Wonder) for the period 2007–2015. The total study sample comprised 28,268,183 live births. Overall, for the four available recorded racial groups (Asian/Pacific Islander, White, American Indian/Alaska Native and Black/African American), M/T rose significantly with increasing education levels (p<0.0001). When analysed by race, this relationship was only found for White births (p<0.0001). The M/T of Black births rose with increasing maternal education level up to associate degree level (p=ns), then fell significantly with higher levels of education (χ 2=4.5, p=0.03). No significant trends were present for Asian/Pacific Islander or American Indian/Alaska Native births. Socioeconomic indicators are generally indicators of better condition and in this study educational attainment was overall found to be positively correlated with M/T, supporting the Trivers–Willard hypothesis.

Corresponding author
Hide All
Almond, D. & Edlund, L. (2007) Trivers–Willard at birth and one year: evidence from US natality data 1983–2001. Proceedings of the Royal Society B: Biological Sciences 274, 24912496.
Chacon‐Puignau, G. C. & Jaffe, K. (1996) Sex ratio at birth deviations in modern Venezuela: the Trivers‐Willard effect. Social Biology 43, 257270.
Ciocco, A. (1938) Variation in the sex ratio at birth in the United States. Human Biology 10, 3664.
Fleiss, J. (1981) Statistical Methods for Rates and Proportions, 2nd edition. John Wiley and Sons, New York, pp. 1415.
Grech, V. (2017) Evidence of socio-economic stress and female foeticide in racial disparities in the gender ratio at birth in the United States (1995–2014). Early Human Development 106–107, 6365.
Grech, V. (2018) A socio-economic hypothesis for lower birth sex ratios at racial, national and global levels. Early Human Development 116, 8183.
James, W. H. (1987) The human sex ratio. Part 1: A review of the literature. Human Biology 59, 721752.
James, W. H. & Grech, V. (2017) A review of the established and suspected causes of variations in human sex ratio at birth. Early Human Development 109, 5056.
Oliver, M. L. & Shapiro, T. M. (2006) Black Wealth, White Wealth: A New Perspective on Racial Inequality. Taylor & Francis, New York.
Pavic, D. (2015) Secular trends and geographical variations in sex ratio at birth. Early Human Development 91, 811815.
Russell, W. (1936) Statistical study of the sex ratio at birth. Journal of Hygiene 36, 381401.
Ryan, C. L. & Bauman, K. (2016) Educational Attainment in the United States: 2015. Population Characteristics. US Census Bureau report P20–578.
Sewell, W. H. & Shah, V. P. (1967) Socioeconomic status, intelligence, and the attainment of higher education. Sociology of Education 40, 123.
Slezák, P., Bokes, P., Námer, P. & Waczulíková, I. (2014) Microsoft Excel add-in for the statistical analysis of contingency tables. International Journal for Innovation Education and Research 2, 90100.
Teitelbaum, M. S. & Mantel, N. (1971) Socio-economic factors and the sex ratio at birth. Journal of Biosocial Science 3, 2342.
Trivers, R. L. & Willard, D. E. (1973) Natural selection of parental ability to vary the sex ratio of offspring. Science 179, 9092.
Visaria, P. M. (1967) Sex ratio at birth in territories with a relatively complete registration. Biodemography and Social Biology 14, 132142.
Winston, S. (1931) The influence of social factors upon the sex-ratio at birth. American Journal of Sociology 37, 121.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Biosocial Science
  • ISSN: 0021-9320
  • EISSN: 1469-7599
  • URL: /core/journals/journal-of-biosocial-science
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed