Altitude, latitude and sex ratio at birth in Iran

Masoudi, Masoud; Saadat, Mostafa

doi:10.1136/jech.2006.050492

Cited by 5 publications

(5 citation statements)

References 2 publications

(1 reference statement)

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“…It was reported that SRB decreased in offspring of male runners 4. Also, there was negative association between SRB and altitude 5. The present finding, however, is not consistent with these reports.…”

contrasting

confidence: 99%

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Offspring sex ratio at birth in mountain climbers

Saadat

Khalili

2009

Journal of Epidemiology & Community Health

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contrasting

confidence: 99%

“…The offspring sex ratio at birth (SRB, the male proportion) of a sample of male runners varied significantly by their weekly training distance 4. Also, it has been reported that SRB was associated with altitude 5. Taken together, it is speculated that offspring SRB mountain climber males may be significantly different from the control group.…”

mentioning

confidence: 99%

Offspring sex ratio at birth in mountain climbers

Saadat

Khalili

2009

Journal of Epidemiology & Community Health

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“…This has been demonstrated in war situations (Graffelman & Hoekstra, 2000;Saadat & Ansari-Lari, 2004;Polasek et al, 2005), and after earthquakes (Fukuda et al, 1998;Saadat, 2008), terrorist attacks (Catalano et al, 2005a(Catalano et al, , 2006 and ecological catastrophes (Mocarelli et al, 2000). Additionally, the sex of a child is partially determined by geographical location (Masoudi & Saadat, 2007), temperature (Helle et al, 2008) and season of birth (Lerchl, 1998;Melnikov, 2003).…”

Section: Introductionmentioning

confidence: 93%

“…Also, parental exposure to environmental hazards, severe stress and other unfavourable conditions affect the sex ratio at birth. Additionally, the sex of a child is partially determined by geographical location (Masoudi & Saadat, 2007), temperature (Helle et al, 2008) and season of birth (Lerchl, 1998;Melnikov, 2003). Additionally, the sex of a child is partially determined by geographical location (Masoudi & Saadat, 2007), temperature (Helle et al, 2008) and season of birth (Lerchl, 1998;Melnikov, 2003).…”

Section: Introductionmentioning

confidence: 99%

Factors Affecting Sex Ratio at Birth in Croatia 1998–2008

Pavić

2012

J. Biosoc. Sci.

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This investigation aims to contribute to the existing literature on demographic and ecological factors affecting the sex ratio at birth, by analysing the births in Croatia from 1998 to 2008. Data from birth certificates for all Croatian births for the investigated period (n=420,256) were used to establish the link between parental ages, birth order, region of birth, parental occupation and parental education level, and sex of the child. The χ² test and t-test were used to assess the significance of each of the factors, along with multiple logistic regression to control for possible confounding effects. The results suggest that a joint higher age of both parents significantly lowers the sex ratio at birth. There is also a regional variation in sex ratio at birth, the lowest value being in Central Croatia and the highest in the City of Zagreb. Changes in the reproductive physiology of older parents are most probably responsible for the lower sex ratio, although the limited sample size warns against widespread generalizations. The causes of the regional variation in sex ratio at birth are most likely the different regional levels of obesity and physical inactivity.

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“…Exposure to smoking 10 , methylmercury 11 , and earthquakes 12 were similarly associated with a reduced sex ratio in observational studies, further indicating that the proportion of male to female live births in a given population may be sensitive to an array of environmental stressors, possibly through inflammatory pathways. Ecologic data also suggest seasonal, altitudinal, and latitudinal sex ratio gradients in some regions of the world, with reduced rates of male live birth at higher lines of latitude, lower altitude, and following periods of cold temperatures [13][14][15][16][17] , implying a potential role of vitamin D, which is synthesized in the epidermis during periods of sun exposure.…”

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confidence: 99%

The role of maternal preconception vitamin D status in human offspring sex ratio

et al. 2021

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Evolutionary theory suggests that some animal species may experience shifts in their offspring sex ratio in response to maternal health and environmental conditions, and in some unfavorable conditions, females may be less likely to bear sons. Experimental data in both animals and humans indicate that maternal inflammation may disproportionately impact the viability of male conceptuses; however, it is unknown whether other factors associated with both pregnancy and inflammation, such as vitamin D status, are associated with the offspring sex ratio. Here, we show that among 1,228 women attempting pregnancy, preconception 25-hydroxyvitamin D concentrations are positively associated with the live birth of a male infant, with notably stronger associations among women with elevated high sensitivity C-reactive protein, a marker of systemic low-grade inflammation. Our findings suggest that vitamin D may mitigate maternal inflammation that would otherwise be detrimental to the implantation or survival of male conceptuses in utero.

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Altitude, latitude and sex ratio at birth in Iran

Cited by 5 publications

References 2 publications

Offspring sex ratio at birth in mountain climbers

Offspring sex ratio at birth in mountain climbers

Factors Affecting Sex Ratio at Birth in Croatia 1998–2008

The role of maternal preconception vitamin D status in human offspring sex ratio

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