Population Dynamics: Fertility, Mortality, and Migration

Posted on Mar 22, 2025 in Geography

Population, Gender, and Age Distribution, Mobility

Background: Populations can change through three processes: fertility, mortality, and migration.

Gender Distribution

  • Masculinity Index (sex ratio): Number of males per 100 females = M/100 F
  • Femininity Index (sex ratio): Number of females per 100 males = F/100 M
  • In the Czech Republic:
    • MI is highest in newborns = 105M/100F
    • MI 35-40 years = 100M/100F
    • MI 80 years = 50M/100F

Age Distribution

Biological Criteria – 3 Generations

  • Children (pre-reproductive): 0-14 years.
  • Parents (reproductive): 15-49 years.
  • Grandparents (elderly, post-reproductive): over 50 years.

3 types of populations can be found (In the Czech Republic there is an old population):

  • Progressive = 400 : 500 : 100 (young)
  • Stationary = 265 : 505 : 230 (balanced)
  • Regressive = 200 : 500: 300 (old)

Working Process Criteria – 3 Generations

  • Pre-productive: 0-14 years.
  • Productive (time of income): 15-59 years (M); 15-54 years (F)
  • Post-productive: >60 years (M); >55 years (F)

WHO Criteria

  • Middle age: 45-59 years.
  • Early old age: 60-74 years.
  • Advanced old age: 75+ years.
  • Longevity: 90+
  • The average (mean) age of population (weighted average) is 35 years (M), 37.5 years (F)
  • Absolutely Growing Population Process: The increase of the number of old population.
  • Relatively Growing Population Process: Older population – the increase of number and also proportion of old population.
  • In Czech Republic = 18% >60 years, 13% >65 years.
  • There is an aging trend in Czech Republic

Natality (Fertility) Measures

  • Crude Birth Rate (CBR): Births per year x 1000/midyear population
  • General Fertility Rate (GFR): Births per year x 1000/midyear female population aged 15-49
  • Age-Specific Fertility Rate (ASFR): Births to women of age X x 1000/midyear female population of age X
  • Total Fertility Rate: Sum of all the Age-Specific Fertility Rates.
  • Crude Reproduction Rate (CRR)
  • Net Reproduction Rate (NRR)
  • Still-Birth Rate: Still-births per year x 1000/live births + still-births per year

Mortality Measures

  • Crude Death Rate (CDR): Deaths per year x 1000/midyear population
  • Age-Specific Death Rate (ASDR): Deaths to people of age X x 1000/midyear population of age X
  • Standardized Mortality Rates: Can be compared in various populations (comparable).
  • Infant Mortality Rate (IMR): Infant deaths under 1 year of age per year x 1000/total live births per year
  • Neonatal Death Rate (infant under 28 days of age).
  • Post-Neonatal Death Rate (infant aged 28 days – 1 year).
  • Perinatal Death Rate: Still births + infant deaths under 7 days x 1000/live births per year
  • Maternal Mortality Rate (MMR): Deaths during pregnancy, labor (delivery) or postpartum per 1000 live births per year

Reproduction Measures

  • Crude Male Rate: Average number of girls (live born) per 1 woman during her reproductive period.
  • Net Exchanger Male Rate: The goal is to keep the simple biological reproduction = 1.
  • Same as Crude M.R. and the girls will live to be in age of their mother of her childbirth – delivery (survive).
  • Abortion (Miscarriage) Rate: Number of abortion / 1000 inhabitants.
  • Abortion Index: Number of abortions / 100 born infants (newborns).

Mobility

  • Natural: Births, deaths
  • Mechanical: Move, migration
  • Socio-legal: Marriages, divorces, abortions