Coupling between death spikes and birth troughs. Part 1: Evidence

Area of Science:

• Demography
• Epidemiology
• Medical Statistics

Background:

• Jacques Bertillon observed a birth dip following the 1889-1890 influenza pandemic.
• This phenomenon, a dip and rebound in births after excess mortality, was not further explored.
• Subsequent mass death events, including influenza pandemics and natural disasters, provide new data to analyze this coupling.

Purpose of the Study:

• To analyze the death-birth coupling phenomenon using data from recent mass death events.
• To understand the factors influencing birth rate fluctuations following mortality crises.
• To explore the predictive power of the death-birth coupling model.

Main Methods:

• Comparative analysis of birth rate data following major mortality events.
• Examination of historical influenza pandemics (1918, 1920) and other crises (1923 Tokyo earthquakes, 9/11 attacks).
• Statistical analysis to identify significant deviations in birth rates attributable to excess mortality.

Main Results:

• A significant birth dip was observed following the 1918 and 1920 influenza pandemics.
• The 9/11 attacks did not show a corresponding dip in birth rates, highlighting the role of collateral sufferers.
• The death-birth coupling model can unify explanations for various birth rate fluctuations, including heat wave impacts.

Conclusions:

• The death-birth coupling is a demonstrable phenomenon influencing population dynamics.
• Collateral suffering plays a critical role in the manifestation of this coupling.
• This model offers a unified framework for understanding and predicting birth rate changes, revealing underlying explanatory factors beyond apparent randomness.