Age-period-cohort analysis of low birth weight, early-term delivery, induction, and cesarean-section, US births

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Updated: Jun 25, 2026

Assessment of Child Anthropometry in a Large Epidemiologic Study
09:36

Assessment of Child Anthropometry in a Large Epidemiologic Study

Published on: February 2, 2017

Chloe A Teasdale1,2, Sean Locke1, Zachary Shahn1,2

  • 1Department of Epidemiology and Biostatistics, City University of New York (CUNY), Graduate School of Public Health & Health Policy (SPH), New York, NY, United States.

American Journal of Epidemiology
|June 24, 2026
PubMed

Insights

Older pregnant individuals (40-44 years) face higher risks for low birth weight (LBW), early term delivery (ETD), and cesarean sections. Recent trends show increased odds for these outcomes, suggesting changes in obstetric care.

Area of Science:

  • Obstetrics and Gynecology
  • Perinatal Epidemiology
  • Public Health

Background:

  • Temporal trends in adverse birth outcomes and delivery modes are influenced by complex age, period, and cohort effects.
  • Understanding these effects is crucial for effective maternal and infant healthcare strategies.

Purpose of the Study:

  • To analyze age, period, and cohort effects on low birth weight (LBW), early term delivery (ETD), induction, and cesarean section rates.
  • To investigate changes in obstetric management for older pregnant individuals (≥40 years).

Main Methods:

  • Age-period-cohort (APC) analysis using US birth records (1994-2019) for singleton, full-term births.
  • APC-interaction method to estimate odds ratios (OR) and 95% confidence intervals (CI) for age, period, and cohort effects.

Main Results:

  • Increased odds of LBW, ETD, induction, and cesarean section were observed for women aged 40-44 years.
  • Higher odds for LBW, ETD, and induction were noted in 2019 compared to the study period average.
  • Specific cohort effects for women aged 40-44 in 2019 indicated elevated odds for ETD, induction, and cesarean section.

Conclusions:

  • Obstetric management for pregnant individuals aged 40 and above has evolved significantly in recent decades.
  • These changes extend beyond expected age and temporal trends, necessitating further investigation into care practices.

Keywords:
APCage-period-cohortc-sectioncohort effectsearly-term deliveryinductionlow birth weightmaternal age

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