Obstetrical intervention and the singleton preterm birth rate in the United States from 1991-2006

Am J Public Health. 2010 Nov;100(11):2241-7. doi: 10.2105/AJPH.2009.180570. Epub 2010 Sep 23.


Objectives: We examined the relationship between obstetrical intervention and preterm birth in the United States between 1991 and 2006.

Methods: We assessed changes in preterm birth, cesarean delivery, labor induction, and associated risks. Logistic regression modeled the odds of preterm obstetrical intervention after risk adjustment.

Results: From 1991 to 2006, the percentage of singleton preterm births increased 13%. The cesarean delivery rate for singleton preterm births increased 47%, and the rate of induced labor doubled. In 2006, 51% of singleton preterm births were spontaneous vaginal deliveries, compared with 69% in 1991. After adjustment for demographic and medical risks, the mother of a preterm infant was 88% (95% confidence interval [CI] = 1.87, 1.90) more likely to have an obstetrical intervention in 2006 than in 1991. Using new birth certificate data from 19 states, we estimated that 42% of singleton preterm infants were delivered via induction or cesarean birth without spontaneous onset of labor.

Conclusions: Obstetrical interventions were related to the increase in the US preterm birth rate between 1991 and 2006. The public health community can play a central role in reducing medically unnecessary interventions.

MeSH terms

  • Adult
  • Birth Rate*
  • Cesarean Section / statistics & numerical data
  • Confidence Intervals
  • Continental Population Groups / statistics & numerical data
  • Delivery, Obstetric / statistics & numerical data*
  • Female
  • Gestational Age
  • Humans
  • Infant
  • Infant Mortality
  • Infant, Newborn
  • Labor, Induced / statistics & numerical data
  • Logistic Models
  • Odds Ratio
  • Pregnancy
  • Premature Birth / epidemiology*
  • United States / epidemiology
  • Young Adult