A statistical analysis of the annual pattern in births in the USA, 1967 to 1976

Randall, Walter

doi:10.1080/09291018709359944

Cited by 9 publications

(2 citation statements)

References 15 publications

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“…Demographers have implicated a host of social, environmental and physiological factors that may interact to drive birth seasonality. While a consensus has yet to be reached, and mechanisms vary geographically, hypothesized drivers include income, culture, race, holidays, rainfall, cold winters and seasonally variable sperm quality [38,[50][51][52][53][54][55][56]. Although we focused on characterizing the variation in birth seasonality, rather than the mechanisms underlying this variation, it is our hope that the latitudinal gradient in peak birth timing and amplitude observed here will help elucidate the primary drivers of birth seasonality.…”

Section: Discussionmentioning

confidence: 99%

Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

et al. 2014

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More than a century of ecological studies have demonstrated the importance of demography in shaping spatial and temporal variation in population dynamics. Surprisingly, the impact of seasonal recruitment on infectious disease systems has received much less attention. Here, we present data encompassing 78 years of monthly natality in the USA, and reveal pronounced seasonality in birth rates, with geographical and temporal variation in both the peak birth timing and amplitude. The timing of annual birth pulses followed a latitudinal gradient, with northern states exhibiting spring/summer peaks and southern states exhibiting autumn peaks, a pattern we also observed throughout the Northern Hemisphere. Additionally, the amplitude of United States birth seasonality was more than twofold greater in southern states versus those in the north. Next, we examined the dynamical impact of birth seasonality on childhood disease incidence, using a mechanistic model of measles. Birth seasonality was found to have the potential to alter the magnitude and periodicity of epidemics, with the effect dependent on both birth peak timing and amplitude. In a simulation study, we fitted an susceptible-exposed-infectedrecovered model to simulated data, and demonstrated that ignoring birth seasonality can bias the estimation of critical epidemiological parameters. Finally, we carried out statistical inference using historical measles incidence data from New York City. Our analyses did not identify the predicted systematic biases in parameter estimates. This may be owing to the well-known frequency-locking between measles epidemics and seasonal transmission rates, or may arise from substantial uncertainty in multiple model parameters and estimation stochasticity.

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Section: Discussionmentioning

confidence: 99%

Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

et al. 2014

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“…It appears to be highest in late fall and early winter and lowest in late spring and early summer (Dabbs 1990). This influences the timing of the seasonal peak for births in August and September-nine months after testosterone levels in men reach their seasonal apex (Randall 1987).…”

Section: Age and Testosteronementioning

confidence: 99%

Leader Age, Regime Type, and Violent International Relations

Horowitz

McDermott

Stam

2005

Journal of Conflict Resolution

101

130

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In this article, the authors investigate the relationship between states'political leaders'ages, their regime type, and the likelihood of militarized dispute initiation and escalation. They examine more than 100,000 interstate dyads between 1875 and 2002 to systematically test the relationship between leader age and militarized disputes. The results show that, in general, as the age of leaders increases, they become more likely to both initiate and escalate militarized disputes. In addition, the interaction of age and regime type is significant. In personalist regimes, the general effect reverses; as age increases, the relative risk of conflict declines in comparison to other types of regimes. Increasing leader age in democracies increases the relative risk propensity for conflict initiation at a higher level than for personalist regimes, while the impact of increasing leader age is most substantial in intermediate regimes.

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The solar wind and human birth rate: A possible relationship due to magnetic disturbances

Randall

1990

Int J Biometeorol

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Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.

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A statistical analysis of the annual pattern in births in the USA, 1967 to 1976

Cited by 9 publications

References 15 publications

Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

Human birth seasonality: latitudinal gradient and interplay with childhood disease dynamics

Leader Age, Regime Type, and Violent International Relations

The solar wind and human birth rate: A possible relationship due to magnetic disturbances

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