There is a marked racial/ethnic disparity in rates of preterm birth in the United States. Nearly 20% of non-Hispanic black women deliver preterm compared with about 13% each among non-Hispanic white women and Hispanic women. Rates of preterm birth have been substantially higher for many years than both state and national averages in a health care system in South Carolina serving a low-income population. In an attempt to lower rates, this health care system offered Centering-Pregnancy group prenatal care starting in March 2009. Centering Pregnancy, a national model of group prenatal care, has shown considerable promise in reducing the rates of preterm birth The only large randomized controlled trial that has evaluated pregnancy outcomes after group care reported that preterm birth rates among women in group care were 33% lower than rates for women who received traditional prenatal care. Rates for black women enrolled in that trial who received group care were 41% lower.
The aim of this retrospective cohort study was to determine the impact of the Centering-Pregnancy model of group prenatal care on rates of preterm birth for women enrolled in group care compared with women receiving traditional prenatal care. Participation in group care was a self-selected choice of the individual patient. Multivariable analysis was used to adjust for potential confounders.
Of the 4083 women in the final study population, 316 were in group prenatal care, and 3767 women had traditional prenatal care. There were no significant differences among women enrolled in group care or traditional care in prenatal risk factors: smoking (16.9% vs 20%; P = 0.17), sexually transmitted diseases (15.8% vs 13.7%; P = 0.29), and previous preterm birth (3.2% vs 5.4%; P = 0.08). The rates of preterm delivery at less than 37 weeks’ gestation and less than 32 weeks’ gestation were significantly lower for group prenatal care: at less than 37 weeks, group care: 7.9% versus traditional care: 12.7% (P = 0.01); and at less than 32 weeks, group care: 1.3% versus traditional care: 3.1% (P = 0.03). The adjusted data showed that that group prenatal care was highly protective for preterm delivery; the adjusted odds ratio was 0.53, with a 95% confidence interval of 0.34 to 0.81. For women in group care, the racial disparity in preterm birth at less than 37 weeks for black women, relative to white and Hispanic women, was no longer significant (P = 0.63).
These findings show that participation in group care reduces the rate of preterm birth compared with traditional care among low-risk women, especially black women.