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Relative influences on recent changes in the first birth ratio in the United States

Rosalind Berkowitz King1

  • 1Demographic and Behavioral Sciences Branch, Center for Population Research, National Institute of Child Health and Human Development, National Institutes of Health, US Department of Health and Human Services, USA.

Journal of Biosocial Science
|March 3, 2004
PubMed

Insights

First-born children are increasingly common in birth cohorts, but the main driver is a rise in childless individuals, not fewer higher-order births. This impacts sibling composition in families.

Area of Science:

  • Psychology
  • Sociology
  • Demography

Background:

  • Psychological research often explores birth order effects on achievement.
  • First-born children have been theorized to have a greater predisposition to achievement.
  • Understanding birth cohort composition is crucial for social and psychological studies.

Purpose of the Study:

  • To analyze changes in birth cohort composition in the United States.
  • To investigate the trend of first-born children relative to higher-order births.
  • To identify the primary factors influencing these demographic shifts.

Main Methods:

  • Utilized a time series analysis of the first birth ratio in the United States.
  • Decomposed the first birth ratio into four key contributing factors.
  • Examined demographic trends from the 1960s onwards.

Main Results:

  • The first birth ratio significantly increased during the 1960s and early 1970s.
  • The ratio showed minimal change in subsequent decades.
  • More recent birth cohorts have a higher proportion of first-borns, but most children are still siblings.
  • The proportion of childless individuals, rather than declining higher-order birth rates, was the main driver of change.

Conclusions:

  • Birth cohort composition has shifted towards a greater prevalence of first-born children.
  • Demographic changes are primarily influenced by an increase in childlessness.
  • Future research should consider these compositional shifts in psychological and sociological studies.

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