Seasonality updated in 28 European/Mediterranean countries: A continuing enigma.

OBJECTIVES: This report updates birth seasonality for 28 European/Mediterranean countries and evaluates the possible influence of atmospheric clarity/quality on seasonality. METHODS: Birth data between 1970 and 2011 were adjusted for seasonality and are presented as conceptions. RESULTS: Presently, 27 of 28 countries have peak conceptions during the last 3 months of the year, a greater concentration than was previously recognized. CONCLUSIONS: There is no apparent explanation for the en masse transition of seasonality, particularly the abrupt change in seasonality for nine countries, The frequency of sexual intercourse might be a one determinant while another possibility might be the decadal changes in atmospheric clearness/quality. However, causal relationships cannot be inferred without further study and/or animal experimentation.

Human birth seasonality and sunshine.

The environmental light intensity/photoperiod (ELI/PP) hypothesis proposes that the seasonality of human births is primarily associated with seasonal changes in ambient atmospheric luminosity or ELI. This study tests for the presence of increased ELI during the 1 or 2-month period preceding the conceptual month. Monthly birth data for Helsinki, Finland; Kiev, Ukraine; Hanoi, Vietnam; Matlab, Bangladesh; Nashville, Tennessee; Los Angeles, California; Dallas, Texas; Denver, Colorado and Pretoria, South Africa, are correlated (Pearsonian r) to corresponding monthly meteorological data. With the exception of Matlab, birth data are adjusted for conception date, 31-day months, leap years and monthly deviation from an annual mean. Meteorological data are adjusted for a 1-2-month exposure to ELI before conception. From these correlations, Helsinki r = 0.82, Kiev r = 0.80, Hanoi r = 0.93, Matlab r = 0.91, Nashville r = 0.84, Los Angeles r = 0.71, Dallas r = 0.86, Denver r = 0.53, and Pretoria r = -82. Weakness and strengths of the ELI/PP hypothesis are reviewed using the criteria developed by AB Hill. Substituting meteorological variables for ELI may be a weakness, whereas the specificity of ELI/PP predictions may be a strength. Increased periods of ELI precede increased periods of conceptions. Increased ELI may influence seasonality for chimpanzee, baboon, and humans. Atmospheric pollution may alter the onset of seasonality. Increased ELI may be the initial, but not the singular variable to affect seasonality.

Complications of local anesthesia used in oral and maxillofacial surgery.

Local anesthetics are used routinely in oral and maxillofacial surgery. Local anesthetics are safe and effective drugs but do have risks that practitioners need to be aware of. This article reviews the complications of local anesthesia. A brief history is provided and the regional and systemic complications that can arise from using local anesthesia are discussed. These complications include paresthesia, ocular complications, allergies, toxicity, and methemoglobinemia. Understanding the risks involved with local anesthesia decreases the chances of adverse events occurring and ultimately leads to improved patient care.

Seasonal sunshine and vitamin D: a possible explanation for differences in European and United States birth patterns.

This study tests whether seasonal differences in the United States and European sunshine is associated with human birth patterns. Birth data are adjusted for 31-day months, leap years, and an annual percentage. Clear observations and birth indices are correlated for European and U.S. cities. With 2-month exposure to clearness, r-values are Chicago (0.63), Bismarck (0.81), Dallas (0.86), Thessaloniki (0.66), and Copenhagen (0.54) and, with 3-month exposure, Amsterdam (0.69). Peak clearness occurs during the autumn for the United States and spring/summer for Europe. Differences in clearness may explain birth pattern differences and reduced U.S. births in the 1930s. Although the effect of vitamin D is plausible, further research is required.

Additional confirmation for the effect of environmental light intensity on the seasonality of human conceptions.

Causality for the seasonality of human births, which affects populations wordwide, has been a profound mystery for nearly two centuries. Most explanations for seasonality fail because of inconsistent global application. In two previous studies, Cummings (2002, 2003) hypothesized that human reproduction has been responsive to changes in both seasonal environmental light intensity (surface luminosity) and photoperiod. Except at higher latitudes, photoperiod is of secondary importance to that of environmental light intensity. Because of a lack of data, the presence or lack of cloud cover is used as a general proxy for environmental light intensity. These studies show a positive correlation between conceptual seasonality and cloud cover on a worldwide basis, and propose that there is a delay between exposure to increased light and the onset of conceptions. This delay is three months at higher latitudes and one to two months for lower latitudes. Both studies suggest that an excellent means of hypothesis confirmation would be to provide one or more examples of how a seasonal change in cloud cover might alter the number of conceptions in subsequent months. The present study tests this hypothesis. The percentage of possible sunshine and averaged sunshine hours are used to investigate their influence on seasonality of births in Germany and the Netherlands. The evidence shows that a seasonal change in environmental light intensity preceded a change in the peak months for conceptions in Germany and the Netherlands. Although secondary influences are possible, the primary reason for this transition in peak conceptual months seems to be related to the seasonal changes in environmental light intensity for both countries. Although this transitional relationship was predicted in Cummings (2002, 2003), further research is required, especially with regard to more precise measurements of environmental light intensity and its physiological effect on the human endocrine system.

The influence of latitude and cloud cover on the seasonality of human births.

BACKGROUND: A previous study (Cummings, 2002), hypothesized that human birth seasonality was primarily related to environmental light intensity/photoperiod. PURPOSE: There are two primary goals: to explain seasonality differences between U.S., Canada, and Europe and to test the influence of environmental light intensity/photoperiod at divergent latitudes. METHODOLOGY: Existing seasonality data were extracted from previous studies at various locations throughout the world. Daily cloud cover amounts (clearness) were utilized as indices for environmental light intensity. DISCUSSION: Results were evaluated and discussed for each sub-study. CONCLUSION: Sub-study results support the hypothesis that human birth seasonality may be influenced by environmental light intensity and photoperiod. This conclusion is supported by logical links between increased light intensity/photoperiod and conceptions at different latitudes. Irrefutable proof may involve correlating long term changes in cloud cover with long term changes in human birth seasonality.