The President Kennedy assassination and the male to female birth ratio

Grech, Victor; Zammit, Dorota

doi:10.1016/j.earlhumdev.2016.08.008

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…These results are consistent with studies suggesting that male fetuses versus females are less likely to survive in suboptimal conditions (34,(59)(60)(61)(62)(63). Decreased male survival in utero in the context of poor maternal conditions has been observed in other mammals (64), and population-level data suggest that the relative number of male births tends to decrease in the context of maternal exposure to earthquakes and social upheaval, including President Kennedy's assassination and the 9/11 terrorist attacks in New York (31)(32)(33)(34)(35)(36). Diminished male fetal survival is poorly understood (59) and not without controversy (38,39).…”

Section: Discussionsupporting

confidence: 87%

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Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes

Walsh

McCormack

Webster

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

159

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Maternal prenatal stress influences offspring neurodevelopment and birth outcomes including the ratio of males to females born; however, there is limited understanding of what types of stress matter, and for whom. Using a data-driven approach with 27 variables from questionnaires, ambulatory diaries, and physical assessments collected early in the singleton pregnancies of 187 women, 3 latent profiles of maternal prenatal stress emerged that were differentially associated with sex at birth, birth outcomes, and fetal neurodevelopment. Most women (66.8%) were in the healthy group (HG); 17.1% were in the psychologically stressed group (PSYG), evidencing clinically meaningful elevations in perceived stress, depression, and anxiety; and 16% were in the physically stressed group (PHSG) with relatively higher ambulatory blood pressure and increased caloric intake. The population normative male:female secondary sex ratio (105:100) was lower in the PSYG (2:3) and PHSG (4:9), and higher in the HG (23:18), consistent with research showing diminished male births in maternal stress contexts. PHSG versus HG infants were born 1.5 wk earlier (P < 0.05) with 22% compared to 5% born preterm. PHSG versus HG fetuses had decreased fetal heart rate–movement coupling (P < 0.05), which may indicate slower central nervous system development, and PSYG versus PHSG fetuses had more birth complications, consistent with previous findings among offspring of women with psychiatric illness. Social support most strongly differentiated the HG, PSYG, and PHSG groups, and higher social support was associated with increased odds of male versus female births. Stress phenotypes in pregnant women are associated with male vulnerability and poor fetal outcomes.

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Section: Discussionsupporting

confidence: 87%

“…Maternal stress also impacts sex at birth such that the typically male-biased SSR (105 male births:100 female births) (30) is diminished in the context of maternal prenatal stress (31)(32)(33)(34)(35)(36), most likely as a consequence of male-sex-selective spontaneous fetal loss (33,34,37). Although the population-level stress-related decrease…”

mentioning

confidence: 99%

Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes

Walsh

McCormack

Webster

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

159

View full text Add to dashboard Cite

show abstract

“…These findings are in fact in line with numerous studies showing the decline of male births in the population following exposures to stressful stimuli such as earthquakes, murders, terrorist acts, stressful work or life-changing events [19][20][21][22][23][24][25][26][27] .…”

Section: Introductionsupporting

confidence: 89%

Hair cortisol levels in pregnancy as a possible determinant of fetal sex: a longitudinal study

Romero-González

Puertas-Gonzalez

González-Pérez

et al. 2021

J Dev Orig Health Dis

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Stress during pregnancy has been widely studied and associated to different variables, usually with negative results for the health of the mother and the newborn, such as having a higher risk of suffering postpartum depression, premature birth, obstetrics complications or low birthweight, among others. However, there are not many lines of research that study the role that the sex of the baby plays on this specific stress and vice versa. Thus, the main objective was to analyse the relationship between the sex of the offspring and the stress of the mothers in the first trimester of pregnancy. In order to achieve this, 108 women had their biological stress measured (trough hair cortisol levels) and psychological stress evaluated (the Prenatal Distress Questionnaire (PSS), the Perceived Stress Scale (PDQ) and the Stress Vulnerability Inventory (IVE)). The results revealed significant differences in maternal hair cortisol levels in the first trimester based on the sex of the baby they had given birth to (t = −2.04; P < 0.05): the concentration of the hormone was higher if the baby was a girl (164.36:54.45-284.87 pg/mg) than if it was a boy (101.13:37.95-193.56 pg/mg). These findings show that the sex of the future baby could be conditioned, among many other variables, by the mother´s stress levels during conception and first weeks of pregnancy. Further research is needed in this area to support our findings.

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Were fewer boys born in the United States during the early months of the COVID‐19 pandemic? A test of the Trivers–Willard hypothesis

Cleaver,

Non

2024

Evolutionary Anthropology

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The Trivers–Willard hypothesis predicts that mammalian parents in poor environmental conditions will favor the offspring sex with more reliable chance of reproductive success, which in humans is females. Three months following the onset of the COVID‐19 pandemic in South Africa, England, and Wales, there were significant decreases in the sex ratio at birth (SRB) (male births/total live births). We analyzed this ratio with a seasonal autoregressive moving average model, and a logistic regression, using nationwide natality data for all singleton births in the United States from 2015 to 2021 (n = 25,201,620 total births). We identified no significant change in the sex ratio in either analysis. Rather, we observed marked differences in the sex ratio by maternal characteristics of race/ethnicity, age, and education, with more vulnerable groups having lower sex ratios. These findings suggest the SRB may be an important marker of reproductive vulnerability for disadvantaged groups in the United States.

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The President Kennedy assassination and the male to female birth ratio

Cited by 8 publications

References 13 publications

Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes

Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes

Hair cortisol levels in pregnancy as a possible determinant of fetal sex: a longitudinal study

Were fewer boys born in the United States during the early months of the COVID‐19 pandemic? A test of the Trivers–Willard hypothesis

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