Preterm birth among American Indian/Alaskan natives in Washington and Montana: comparison with non-Hispanic Whites.

Preterm birth is the single most important cause of perinatal mortality in North America. Given that American Indians/Alaskan Natives (AI/ANs) in the United States continue to have adverse birth outcomes, the purpose of this study is to compare the risk of preterm birth among AI/AN mothers to Non-Hispanic White mothers living in Washington and Montana from 2003 to 2009. A population-based retrospective cohort study was conducted examining the association between AI/AN mothers (self-reported) and the risk of preterm birth (gestational age <37 weeks) using birth certificate data from Washington and Montana. All AI/AN singleton lives births (n = 26,648) from residents of Washington and Montana from 2003 to 2009 were identified and included in our study. An identical number of Non-Hispanic White singleton infants (n = 26,648) born to residents of Washington and Montana were randomly selected as a comparison group and logistic regression was used to analyze the data. AI/AN mothers living in Washington and Montana between 2003 and 2009 were 1.34 times (95 % CI 1.25-1.44) as likely to have a preterm birth compared to Non-Hispanic Whites after adjusting for maternal and paternal characteristics as well as pregnancy risk factors. AI/AN mothers residing in Washington and Montana from 2003 to 2009 were at a significantly increased risk of having a preterm birth compared to Non-Hispanic Whites. Identifying etiologic differences in preterm birth experienced by AI/ANs is essential in targeting future interventions.