The sex ratio at birth in South Africa may be a sentinel health indicator.
The sex ratio at birth is commonly expressed as M/T, denoting male births divided by total births. Males are almost invariably born slightly in excess. Stress and negative socioeconomic conditions lower M/T and this has been mooted as a possible reason for the observed low M/T for Black births worldwide. South Africa is experiencing a period of economic prosperity. This study was carried out in order to ascertain whether improving conditions in South Africa as measured by available health indicators, were associated with a rise in M/T in this country.



Annual male and female births were obtained from Statistics South Africa along with key health indicators: total fertility rate, life expectancy, infant mortality and under 5year mortality, for 2003-2014.



There were a total of 12,409,437 births (M/T 0.5035, 95% CI 0.5032-0.5037). There was a rise in M/T over the initial period studied (2003-2010) with a plateau thereafter. The rise over the entire period studied was significant (Chi for linear trend=30.3, p<0.0001). M/T was significantly positively correlated with life expectancy and significantly negatively correlated with infant mortality, under 5year mortality and total fertility rate.



It has been mooted that the lower M/T observed in Blacks may be stress-related. The observed rise in M/T associated with health improvements in South Africa support this contention. Moreover, this study suggests that M/T may serve as a sentinel health indicator, and may not only highlight adverse conditions through its decline, but also improvements in overall conditions with its rise.
Academic Department of Paediatrics, Medical School, Mater Dei Hospital, Malta. Electronic address: victor.e.grech@gov.mt.
Victor
V
Grech
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Department of Obstetrics and Gynecology, University College Cork, Cork, Ireland; Gravida: National Centre for Growth & Development, University of Auckland, Auckland, New Zealand; Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. Electronic address: parturitions@gmail.com.
Gwinyai
G
Masukume
D003906:Developing Countries / Q000191:economics / Q000706:statistics & numerical data; D005260:Female; D006304:Health Status; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D012744:Sex Ratio; D012959:Socioeconomic Factors; D013019:South Africa
Birth rate/*trends; Infant, newborn; Sex ratio; South Africa