PURPOSE: The purpose of Early Selection and Sex Composition in Italy is to try to investigate whether socioeconomic, cultural, or Biological factors still influence the sex ratio at birth in four Italian regions. APPROACH: The author of this article, L. A. Zonta, along with his partners P. Astolfi and L. Ulizzi, chose four Italian regions with different degrees of industrialization and socioeconomic levels to study environmental differences in the sex ratio.
The studied the still birth rate and the relations between newborn viability and sex composition as a function maternal age and educational levels. The author looked at studies that had been completed as early as 1662 by J. Grant that reported an excess of male births (415). They realized that many researchers have investigated patterns of sex ratio deviations from the 1: 1 ratio however; many of these investigations do not include a high number of factors that seemingly affect sex ratios. Zonta gives a short description of previous studies that the authors have conducted like analyzing the sex ratios at birth and one year in representative populations of different ethnic groups and the partitioning of sex ratio variability in the Italian population over two generations (416). Here, they report on the environmental determinants of the sex ratio variability in a sample of Italian regions.
Italy was chosen, as stated by the author on page 416, because “Italy is particularly suitable for evaluating the extent of environmental effects on quantitative variables, such as the sex ratio, because in general socioeconomic conditions deteriorate following an almost north to south cline, The region, which correspond to major administrative geographic subdivisions… have been under heterogeneous conditions of industrialization and the associated health revolution, two examples of determinants that influence the secondary sex ratios. FINDINGS: The authors looked at several different factors to reach their general conclusion. In looking at sex ratio secular trend, it was found that the excess of male extra mortality, leaving sex ratios with similar values. In a regional lever, it is shown that sex composition at birth can be maintained almost unaltered to reproductive age (420). In looking at factors influencing sex composition at birth, it is shown that the distributions of maternal age at delivery, maternal education level, and stillbirth rate showed a positive relationship with maternal age and a negative relationship with maternal educational level (420).
In grouping Lombardy and Latium versus Campania and Sardinia, it was confirmed that dependency on viability on age and education distributions was not significantly different between the two regions. Basically, in the Lombardy and Latium regions, mortality at birth is higher in women with lower educational backgrounds and it increases equally in both sexes, and it is not significant with the age of the mother (425). In the Campania-Sardinia regions, the increase is statistically significant and higher in women over 30 years of age with a low education level (425). Children born to older, unacculturaterd/Uneducated mothers have a higher stillbirth rate in males than among females.
GENERAL CONCLUSION: In general, it was found that in less favorable environments early selection against male newborns is almost twice that against female new born’s when the mothers are the least favored for socioeconomic status, cultural level, and biological conditions (older that 39 years) (415). Despite the increasing homogenization of the four regions, significant discrepancies exist between the regions with different socioeconomic levels (425). It could be said then, that interactions among socioeconomic, socioeconomic levels (425). It could be said then, that interactions among socioeconomic, , cultural, and biological factors may still influence the population sex ratio.
In analyzing the four regions, it seems that in regions with a higher standard of living, such as Lombardy and Latium, early selection against male newborns is almost twice that against female newborns. In poorer socioeconomic regions such as Campania and Sardinia, maternal age can prove to be of great importance. The authors determine in the end that “these results suggest that even nowadays in unfavorable environments natural selection has relevant effect of the sex ratio at birth through male-specific extra mortality (425).”.