Abstract
In this study, the human secondary sex ratio (described as the number of males per 100 female births) in Ondo, a town in South -West Nigeria was analyzed using birth record between 2001 and 2008, obtained at State Specialist Hospital. The analysis of the 11,426 births recorded during the period revealed a secondary sex ratio of 1.14, that is, 114 boys for every 100 girls born. There was a strong correlation (0.236**) between sex ratio and birth outcome indicating that gender has strong influence on child survival. There is however no significant relationship between the sex of baby and the season of birth as the ratio of male to female babies remains unchanged through the seasons. This study reports the first information on secondary sex ratio in Ondo town and gives impetus for further investigations into factors affecting secondary sex ratio among the populations at the study area.
Highlights
Animals have demonstrated significant variations in the proportion of male to female that are born, even though individuals expend approximately equal efforts on male and female reproductive functions [1]
[2] The sex chromosomes segregate during meiosis in males, it is expected that the human sex ratio would be 1:1 [2]; but on the contrary, the values obtained from studies of human populations across the world show that the expectation is not universal owing to several reasons [3,4,5,6,7]
The secondary sex ratio in the population under study was 114:110; a value higher than those reported for South-West Yoruba populations
Summary
Animals have demonstrated significant variations in the proportion of male to female that are born, even though individuals expend approximately equal efforts on male and female reproductive functions [1]. The mechanisms underlying these differences are unclear. In the absence of manipulations, the sex ratio is remarkably consistent across human populations with an average of 105-107 male births for every 100 female births. Reduced survivals of male progeny before and after birth is a general finding in mammals especially humans amongst whom malebiased age-specific morbidity and mortality remain prominent during conception, neonatal life and infancy, adolescence and adult life. Several environmental and demographic factors affect sex ratio distribution across human populations, these include; coital frequency [8,9] birth order [10,11] paternal age [12,13,14] maternal weight and diet [15,16,17], maternal age [18], hormones [19,20], polygyny, [9,21] latitude [19,21], war [20,22], exposure to environmental pollutants [23,24,25,26,27,28], illhealth [29,30], parity [31,32,33], seasonal variation [34,35], religion [36], race [18,37,38] and sex selective abortions [6,39,40,41]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
