690: Racial disparities in preterm birth risk by risk factor grouping

Abstract

To examine racial/ethnic differences in risk of preterm birth (PTB, < 37 weeks) among women with known risk factors. We used the California Birth Cohort Database for live births maintained by the California Office of State Health Planning and Development. Our sample included singleton deliveries between 20-44 weeks gestation among non- Hispanic “Black”, “Hispanic” White, and non-Hispanic “White” women. Risk groups were classified using ICD-9 codes for previous PTB, any hypertension, preeclampsia, any diabetes, infection, mental illness, smoking, and drug or alcohol dependence. We used logistic regression to compare odds of PTB in Black and Hispanic compared to White women among women who had none of these risk factors and among women with each risk factor. All models were adjusted for other risk factors and for maternal age, interpregnancy interval, education, obesity, and poverty status. 2,320,020 women were included in this analysis (7% Black, 61% Hispanic, and 32% White). PTB rates were higher among Black (9.9%) and Hispanic (6.9%) women compared to White women (6.0%, adjusted odds ratio [aOR] = 1.5 and aOR = 1.3, respectively). While PTB rates across risk groups differed dramatically (wherein the highest rates were among Black and Hispanic women with preeclampsia (33.0% and 29.5%, respectively)) or previous PTB (30.5% and 29.6%, respectively)), the magnitude of the disparities remained consistent for Black and Hispanic women compared to White women across most risk factor groupings (aORs 1.4 to 1.6 for Black versus White women and 1.2 to 1.3 for Hispanic versus White women). Exceptions included women who had a previous PTB (aOR of 1.1 for Black versus White women), any hypertension (aOR 1.5 for Hispanic versus White women), or smoked (aOR 1.1 for Hispanic versus White women). While all risk factors were associated with an increased risk of PTB across race/ethnicity groupings, these racial/ethnic disparities remained fairly similar suggesting that others factors (e.g., stress, racism) are driving disparities.