Trends and predictors of preterm birth among Asian Americans by ethnicity, 1992-2018

Background In an increasingly diverse United States (US) population, racial disparities in preterm birth outcomes continue to widen. Objective In this study, we examined temporal trends and risk of preterm birth among Asian American women over a quarter century (1992-2018). Study design This is a retrospective cohort study using the 1992-2018 Natality data files. We conducted joinpoint regression analyses to examine trends in preterm birth among Asian Americans and non-Hispanic (NH) Whites. Bivariate and multivariable analyses were used to identify risk factors associated with preterm birth among Asian Americans and their ethnic sub-groups as compared to NH-Whites. Results There were a total of 251,278 preterm births among Asian American women, corresponding to a rate of 10.0%, which was relatively stable over time. The incidence of extremely, very and moderate-to-late preterm birth among Asian Americans was 0.4%, 0.9% and 8.7% respectively. Overall, Asian American women exhibited lower adjusted odds (OR = 0.92; 95% CI: 0.88-0.97) of preterm birth than their NH-White counterparts. Comparing Asian American subgroups to NH-Whites, Filipinas and Vietnamese mothers had increased adjusted odds, whereas Chinese, Korean, Japanese and Asian Indian women showed decreased adjusted odds for preterm birth. Conclusion The risk of preterm birth varied among the ethnic subgroups of Asian Americans in the United States. Future studies should explore the socio-cultural and environmental nuances that might explain these differences.