Author(s): MacDorman MF, Declercq E, Zhang J
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.Gynecology & Obstetrics