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2015, Science Journal of Public Health
The sex ratio at birth (SR) is defined as the number of males per 100 females and is almost always around 106. John Graunt (1620Graunt ( -1674 was the first to compile data showing an excess of male births to female births and to note spatial and temporal variation in the SR. John Arbuthnot (1667-1735) demonstrated that the excess of males was statistically significant and asserted that the SR is uniform over time and space. Arbuthnot suggested that the regularity in the SR and the dominance of males over females must be an indication of divine providence. Nicholas Bernoulli's (1695-1726) counter-argument was that chance could give uniform dominance of males over females. Later, Daniel Bernoulli (1700-1782), Pierre Simon de Laplace (1749-1827) and Siméon-Denis Poisson (1781-1840) also contributed to this discussion. Attempts have been made to identify factors influencing the SR, but comparisons demand large data sets. Attempts to identify associations between SRs and stillbirth rates have failed to yield consistent results. A common pattern observed in different countries is that during the first half of the twentieth century the SR showed increasing trends, but during the second half the trend decreased. A common opinion is that secular increases are caused by improved socio-economic conditions. The recent downward trends have been attributed to new reproductive hazards. Factors that affect the SR within families remain poorly understood. Although they have an effect on family data, they have not been identified in large national birth registers.
Statistica, 2015
Variations in sex ratios at birth is still an active research field and several studies in the last decades have focused on this topic. In this article, studies on the main determinant of long- and short-term trends are briefly reviewed, taking into account findings and results from different kinds of disciplines. In his early studies, Corrado Gini concluded that the human sex ratio at birth was universally stable, without significant fluctuations across time and space. However, in the last decades several authors have directly challenged these conclusions. Therefore, after summarizing the results of Gini’s research on the historical trends of the sex ratio at birth, a brief review focuses on the analyses of contemporary trends. The main determinants of the variations of the sex ratio at birth in time and space mentioned in the literature and the corresponding theoretical explanations are summarized. Special attention is paid to the recent studies on the impact of the environment, p...
The paper published by Poisson in 1830 marks the point from which the history of the calculation of sex ratio at birth and that of the analytical calculus of probabilities, while remaining intimately connected, began to gain a certain degree of autonomy from each other. It is true that, decades later, the mathematician Wilhelm Lexis (1837–1914) and the sociologist Maurice Halbwachs (1877–1945) came to reexamine , each in his own way, the relationship of the concrete regularity of this type of observation to the formal abstraction presupposed by the mathematical analysis of chances (Halbwachs, 1936 [2005]; Lexis, 1876; Stigler, 1986). But, after its rewriting by Poisson, and then for more than a century, the calculus of probabilities was regarded by the most influential. The global success of the Internationl Congress of Statistics, animated by Ad. Quételet, has forged the know how of statisticians, later demographers, on the topic.
Early Human Development, 2015
The factors that influence the male to female ratio at birth are legion. Males are usually born in excess and stress decreases the ratio while wellbeing and good health tends to increase it. This paper reviews the multitudes of factors that have been implicated as affecting this ratio, from historical times to date.
Since the 18th century, one phenomenon – the degree of regularity of the proportion of the sexes at birth – has contributed elements of support to various developments such as the calculus of probabilities, administrative statistics, the moral and social sciences, the statistics of variability, post-Darwinian biology and even Durkheimian sociology. We should add that, over three centuries, they have often crossed paths, sometimes keeping a fair trade going, but also laying themselves open to other objects being smuggled in. In this book, we have attempted to explore the phenomenon itself through a history of the way it has been understood by scholars – a history that is a reconstruction of the forms taken by the rational control of technical and conceptual operations, as faithful as historiography will allow us to be. As we come to the end of what might therefore be described as an epistemological and historical deconstruction of human sex ratio at birth, the various pathways that we have followed through what seems in retrospect to be a history of the relationships between certain areas of mathematics , biological sciences and social sciences have given us a panoply of means that we have finally been able to recombine effectively with new reconstructions in mind.
Environmental Health Perspectives, 2001
Second chapter of : E. Brian and M. Jaisson, The Descent of Human Sex Ratio at Birth. Once the analytical calculus of probabilites established, once the civil state apparatus established too, the controversies between doctors, administrative clercs, mathematicians are analysed here, including a fable promoted by Quetelet's that has governed most of the 19th Century works.
Dealing with Human sex ratio at birth Darwin used the statistical material produced by the 'avalanche of numbers' of his time being. But in a different way from statisticians and demographers. According to his theory of evolution, he has focussed on variability, not on consistency of the ratio. Here is the crossroads, on the one hand to the biological approach, on the other to descriptive statistcs, and last to probabilist approaches. They all deal with the same phenomenon, and each of them have settled specific disciplinary know how and traditions. From this split reactivated today in disciplinary claims, comes the tensions between biological approaches of sexuality and approaches of gender in social sciences.
Journal of Epidemiology & Community Health, 2003
This chapter of The Descent of Human Sex ratio at Birth, Springer, 2007, formulates two brand new proposals found working on the French book : "Le sexisme de la première heure, Paris, Raison d'agir, 2007 (same tandem of authors). Proposal 1. How to use an analysis of historical epistemology covering four Centuries in order to built Something new providing results. Proposal 2. Here, this "Something new" is a stochastics definition of social and anthropological facts. Let's consider this paradigmatic example. For each individual birth, involving the reproduction of everyone around, at any scale from the family to humanity as a whole, the distinction of reproductive device turns around 50/50. So when a gender is attributed to the new born (or next future new born) this is first and foremost a collective response in front of this necessary randomness. The intensity of the collective response is variable and measurable (examples are provided in the book). The symbolic strength of the gender attribution comes from this intensity. To tell it otherwise : when the family, everyone around, etc. tells "it's a girl (or a boy)" the message is" it's INDEED a whatever", and our future (the future of the family, and every one arond) is secure. If gender issues are so hot in the intimacy and on the public place, including in the scientific communauties, it is because touching this symbol is as playing at random against these future. (abstract by EB, december 2016).
Human Reproduction, 2001
This document – to be considered as an appendix to the books The Descent of human sex ratio at Birth. A Dialogue between Mathematics, Biology and Sociology (Dordrecht, Springer Verlag, 2007), and Le Sexisme del a première heure (Paris, Raisons d'agir, 2007). The ratio of the number of boys for one hundred girls born is criticized. And based on a the simpler and more robust proportion of the births of one of two sexes on the total of births, models of dumped oscillators are built and improved far cases like China (20th Cent.), France (19th and 20th Cent.) or Japan (20th Cent.). The paper as been partially published as the appendix D of the book "The Descent of human sex ratio at birth" (2007), see in the section "books" and on Springer Link, in the "back matter" of this book.
Journal of Biosocial Science, 2011
We thank Dr James for his always stimulating comments on variations in the sex ratio at birth. Dr James makes some specific comments and queries about our interpretation of the Lexis variations that we found in data from both Europe and Africa. These Lexis variations (different probability of bearing a boy among couples) were shown primarily by a statistical analysis of the distribution of boys and girls according to the number of males and female already born in the family . In another paper, we showed Poisson variations by age of mother and birth order using the same African data . We fully agree with Dr James that any systematic Poisson variation will have only a minor effect on the variance of the distribution of boys and girls in families. We have also addressed the issue of behavioural factors in a comment to a study based on American data .
Introduction and overview of the book published by the authors : The Descent of Human Sex Ratio at Birth, Springer, 2007.
Journal of Biosocial Science, 1970
Summary and conclusionsTo summarize the findings presented here, only three of the five factors studied appear to be independently related to the sex ratio at birth. The significant negative birth-order effect, which in the first analysis accounted for a 2·6% shift in the relative odds of male birth, remained significant when adjustment for the race effect was provided in the second analysis. The magnitude of the effect was diminished by this adjustment, however, indicating that analysis for birth-order effects in the absence of adjustment for the race factor may lead to over-estimates of the importance of the birth-order factor.The significant race effect detected in the second analysis resulted in a 3% lower relative odds for a Negro male birth than that for a white. This racial difference, coupled with the non-uniform distribution of Negro births by paternal-age and birth-order categories, appears to be the source of the mysterious ‘interaction effect’ between birth order and pat...
After an analyses of the reasons why Comte and Durkheim have excluded the probabilistic understanding of statistics from the definition of what a social fact is, the work of Maurice Halbwachs is examined. He realized that the study of the human sex ratio at birth (1933-1936) was opening a way to enhanced Durkheimian objectivism. But his researches attracked the attention of two German statisticians of the time who where not interested by Halbwachs' theoretical issues, but competing in the context of nazi institutions. One of them, the SS Korherr, imagined to use the SS as experimental body for testing his understanding of the sex ratio issues forged among statisticians during the 19th Century. Typical of computing without thinking, or with thinking in a perverse manner.
Demography, 1974
This paper examines the values, variance and some possible determinants of sex ratios for the first child and for all children in expected and desired families. For adults in Tallahassee, Florida, it was found that a large majority of respondents within sixty demographic categories chose males for their first child. Of those who actually had girls for their first child, a plurality would, nevertheless, prefer a first boy in their desired family. It was hypothesized and demonstrated that sex-role ideologies were a strong predictor of variance in first-child sex preferences. Sex ratios for all children in expected and desired families were 116 and 113, respectively. If people could choose the sex of their future children, these data suggest that several population parameters might be significantly altered; a preliminary model is outlined which might project some of these changes.
Proceedings of the National Academy of Sciences of the United States of America, 2015
We describe the trajectory of the human sex ratio from conception to birth by analyzing data from (i) 3- to 6-d-old embryos, (ii) induced abortions, (iii) chorionic villus sampling, (iv) amniocentesis, and (v) fetal deaths and live births. Our dataset is the most comprehensive and largest ever assembled to estimate the sex ratio at conception and the sex ratio trajectory and is the first, to our knowledge, to include all of these types of data. Our estimate of the sex ratio at conception is 0.5 (proportion male), which contradicts the common claim that the sex ratio at conception is male-biased. The sex ratio among abnormal embryos is male-biased, and the sex ratio among normal embryos is female-biased. These biases are associated with the abnormal/normal state of the sex chromosomes and of chromosomes 15 and 17. The sex ratio may decrease in the first week or so after conception (due to excess male mortality); it then increases for at least 10-15 wk (due to excess female mortality)...
Human Reproduction, 2012
background: Previous studies suggest that stressful pregnancies may be associated with a lower proportion of male relative to female offspring. Low or high maternal age may represent stress for the fetus. Our aim was therefore to study whether the sex ratio differs by maternal age in all pregnancies, and in separate analyses, to assess the sex ratio in pregnancies complicated by pre-eclampsia, fetal death, preterm delivery or small for gestational age (SGA) offspring. methods: Data from all births in Norway from 1967 through 2006, a total of 2 206 040 births, were used to estimate sex ratios (the number of male per 100 female offspring) according to maternal age. The analyses were done among all pregnancies, and within subgroups of complicated pregnancies. In addition, we estimated the odds ratio (OR) of having a male offspring by maternal age in all pregnancies with adjustment for pre-eclampsia, fetal death, preterm delivery or SGA offspring. results: Overall, there was no association of maternal age with the human sex ratio. In subgroups of complicated pregnancies (pre-eclampsia, fetal death, preterm delivery and SGA offspring) the sex ratio was increased. However in pregnancies with pre-eclampsia, the proportion of males decreased with increasing maternal age. In multivariable analyses including all pregnancies, with adjustment for complications, there was still no association of maternal age with offspring sex. However, in pregnancies with SGA offspring, the adjusted OR of delivering a boy at term was lower than expected (OR 0.87, 95% confidence interval 0.85-0.89). conclusions: The lower proportion of male births at high maternal age in pregnancies with pre-eclampsia and in pregnancies with live born SGA offspring born at term, supports the hypothesis that male fetuses are more vulnerable to maternal stress than female fetuses. The main limitation of our findings is lack of statistical power due to small study subpopulations.
The almost constant proportion of boys and girls at birth has intrigued several scientists active in learned societies during the Enlightenment : Graunt, Arbuthnot, Sussmilch, d'Alembert, Laplace, Condorcet and others tried to deal with it. It is thus during this Century that the conceptions of the physics of this phenomenon, considered as related to physico-theology, is confronted to reflections on the scope and relevance of the calculations of probabilities.
Journal of Environmental and Occupational Health
A series of recent publications discussed an increase in the male-to-female (M/F) ratio at birth supposedly under the impact of radiation from nuclear tests and accidents. However, social factors have not been sufficiently analyzed. Additional doses due to the radioactive contamination have usually been negligible compared to the natural background radiation. Bias is not excluded in epidemiological studies of low-dose radiation: surveillance and recall bias, dose-dependent selection, and self-selection. Among others , ideological bias is aimed at a strangulation of nuclear energy production. One of the main causes of the elevation of M/F ratio at birth in certain regions is the son preference and sex-selective abortions after a prenatal ultrasonic gender testing. Migrations contribute to a global M/F shift. A relatively high M/F ratio prior to the introduction of the ultrasonic testing is an indication to other perinatal sex selection methods, e.g., female neonaticide and abandonment of newborn girls. Besides, reduced M/F ratio has been associated with an older age at childbearing. In conclusion, the hypothesis that anthro-pogenic elevation of the radiation background contributed to the skewing of M/F ratio toward males is unproven. Dose-response relationships at low radiation doses should be studied in large-scale animal experiments applying dose rates comparable to those in humans.
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