The rise in singleton preterm births in the USA: the impact of labour induction

BJOG. 2012 Oct;119(11):1309-15. doi: 10.1111/j.1471-0528.2012.03453.x. Epub 2012 Aug 13.


Objective: To assess the extent to which increased rates of labour induction and caesarean section have contributed to the recent rise in preterm birth.

Design: National birth cohort study.

Setting: USA.

Population and sample: Singleton live births, with primary analysis based on non-Hispanic white women.

Methods: Ecological study based on the 50 states and the District of Columbia during two time periods 10 years apart: 1992-94 and 2002-04.

Main outcome measure: Preterm birth (live birth <37 completed weeks of gestation), based on an algorithm combining menstrual and clinical estimates of gestational age.

Results: The state-level ecological analysis among non-Hispanic white women showed that the change in preterm birth rate from 1992-94 to 2002-04 was significantly associated with the change in rate of labour induction (r = 0.50, 95% CI 0.26-0.68), but not with the change in rate of caesarean delivery (r = -0.06, 95% CI -0.33 to 0.22). Weaker but otherwise similar associations with labour induction were observed in Hispanic women and in non-Hispanic black women.

Conclusions: Increasing use of labour induction is probably an important cause of the observed increased rate in preterm birth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Algorithms
  • Cesarean Section / adverse effects*
  • Cohort Studies
  • Female
  • Gestational Age
  • Humans
  • Labor, Induced / adverse effects*
  • Pregnancy
  • Premature Birth / epidemiology*
  • Premature Birth / etiology
  • Risk Factors
  • United States / epidemiology
  • Whites
  • Young Adult