524: Preterm birth occurrence among Asian women relative to their place of birth

Abstract

To investigate preterm birth (PTB) rates between United States (US-born) vs. foreign-born Asian women. We hypothesized that foreign-born Asian women would have lower PTB rates compared to their US-born counterparts, irrespective of women’s specific country of origin. Linked birth certificate and maternal discharge data were used to identify nulliparous women with a singleton livebirth and Asian race in California between 2007-2011. PTB was defined as a delivery at less than 37 weeks gestation and further divided into spontaneous and medically indicated PTB. The rate of PTB was examined by self-reported race and place of birth among the following Asian subgroups: Chinese, Japanese, Korean, Vietnamese, Cambodian, Thai, Laotian, Hmong, Indian and Filipino. We observed lower overall PTB rates among foreign-born compared to US-born Asian women in nine out of ten subgroups, whereas, foreign-born Hmong women had a higher PTB rate compared to US-born Hmong women. There were marked differences in PTB rates between the individual Asian subgroups: Korean women had a very low PTB rate (4.2% foreign-born vs. 5.2% US-born Korean) whereas both foreign-born and US-born Filipino women had almost twice as high PTB rates (10.2% foreign-born vs. 10.8% US-born Filipino). Spontaneous PTB also occurred less frequently among foreign-born Asian women compared to US-born Asian women across all other Asian subgroups except among Hmong women. The rates of medically indicated PTB were similar among the foreign-born vs. US- born Asian women. (Table) Among specific Asian subgroups examined, women who were foreign-born had lower overall PTB rate and spontaneous PTB rate compared to US-born Asian women. We observed wide variation in PTB rates between Asian subgroups. Further inquiry is needed to assess factors contributing to such differences.