Fernandez et al. Respond to "Natural Versus Unnatural Sex Ratios"

Fernández, Silvia Josefina Venero; Medina, Ramón Suárez; Britton, John; Fogarty, Andrew

doi:10.1093/aje/kwr361

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…Wilcox and Baird question the importance of the sex ratio as an environmental health indicator and try to explain the strong increase in the sex ratio in Cuba by sex selective abortions [37]. Abortions in Cuba have been described in the scientific literature [38] but not gender-specific ones [39]. Therefore, the alternative explanation offered by Wilcox and Baird, sex selective abortion, is implausible as this practice is unusual in Cuba.…”

Section: Sex Ratio In Cuba After Chernobylmentioning

confidence: 99%

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

2013

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BackgroundThe ratio of male to female offspring at birth may be a simple and non-invasive way to monitor the reproductive health of a population. Except in societies where selective abortion skews the sex ratio, approximately 105 boys are born for every 100 girls. Generally, the human sex ratio at birth is remarkably constant in large populations. After the Chernobyl nuclear power plant accident in April 1986, a long lasting significant elevation in the sex ratio has been found in Russia, i.e. more boys or fewer girls compared to expectation were born. Recently, also for Cuba an escalated sex ratio from 1987 onward has been documented and discussed in the scientific literature.Presentation of the hypothesisBy the end of the eighties of the last century in Cuba as much as about 60% of the food imports were provided by the former Soviet Union. Due to its difficult economic situation, Cuba had neither the necessary insight nor the political strength to circumvent the detrimental genetic effects of imported radioactively contaminated foodstuffs after Chernobyl. We propose that the long term stable sex ratio increase in Cuba is essentially due to ionizing radiation.Testing of the hypothesisA synoptic trend analysis of Russian and Cuban annual sex ratios discloses upward jumps in 1987. The estimated jump height from 1986 to 1987 in Russia measures 0.51% with a 95% confidence interval (0.28, 0.75), p value < 0.0001. In Cuba the estimated jump height measures 2.99% (2.39, 3.60), p value < 0.0001. The hypothesis may be tested by reconstruction of imports from the world markets to Cuba and by radiological analyses of remains in Cuba for Cs-137 and Sr-90.Implications of the hypothesisIf the evidence for the hypothesis is strengthened, there is potential to learn about genetic radiation risks and to prevent similar effects in present and future exposure situations.

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Section: Sex Ratio In Cuba After Chernobylmentioning

confidence: 99%

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

2013

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Response to F. Bochud and T. Jung: Comment on the human sex odds at birth after the atmospheric atomic bomb tests, after Chernobyl, and in the vicinity of nuclear facilities, Hagen Scherb & Kristina Voigt, Environ Sci Pollut Res (2011) 18:697–707 (DOI: 10.1007/s11356-012-0767-6)

Scherb

Voigt

2012

Environ Sci Pollut Res

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Economic stress or random variation? Revisiting German reunification as a natural experiment to investigate the effect of economic contraction on sex ratios at birth

Schnettler

Klüsener

2014

Environ Health

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BackgroundThe economic stress hypothesis (ESH) predicts decreases in the sex ratio at birth (SRB) following economic decline. However, as many factors influence the SRB, this hypothesis is difficult to test empirically. Thus, researchers make use of quasi-experiments such as German reunification: The economy in East, but not in West Germany, underwent a rapid decline in 1991. A co-occurrence of a decline in the East German SRB in 1991 has been interpreted by some as support for the ESH. However, another explanation might be that the low SRB in 1991 stems from increased random variation in the East German SRB due to a drastically reduced number of births during the crisis. We look into this alternative random variation hypothesis (RVH) by re-examining the German case with more detailed data.MethodsOur analysis has two parts. First, using aggregate-level birth register data for all births in the period between 1946 and 2011, we plot the quantum and variance of the SRB and the number of births and unemployment rates, separately for East and West Germany, and conduct a time series analysis on the East German SRB over time. Second, we model the odds for a male birth at the individual level in a multiple logistic regression (1991–2010, ~13.9 million births). Explanatory variables are related to the level of the individual birth, the mother of the child born, and the regional economic context.ResultsThe aggregate-level analysis reveals a higher degree of variation of the SRB in East Germany. Deviations from the time trend occur in several years, seemingly unrelated to economic development, and the deviation in 1991 is not statistically significant. The individual-level analysis confirms that the 1991-drop in the East German SRB cannot directly be attributed to economic development and that there is no statistically significant effect of economic development on sex determination in East or West Germany.ConclusionOutcomes support the RVH but not the ESH. Furthermore, our results speak against a statistically significant effect of the reunification event itself on the East German SRB. We discuss the relative importance of behavioral and physiological responses to macro-level stressors, a distinction that may help integrate previously mixed findings.

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Fernandez et al. Respond to "Natural Versus Unnatural Sex Ratios"

Cited by 3 publications

References 3 publications

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

Increased sex ratio in Russia and Cuba after Chernobyl: a radiological hypothesis

Response to F. Bochud and T. Jung: Comment on the human sex odds at birth after the atmospheric atomic bomb tests, after Chernobyl, and in the vicinity of nuclear facilities, Hagen Scherb & Kristina Voigt, Environ Sci Pollut Res (2011) 18:697–707 (DOI: 10.1007/s11356-012-0767-6)

Economic stress or random variation? Revisiting German reunification as a natural experiment to investigate the effect of economic contraction on sex ratios at birth

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