Preterm delivery rates within industrialized countries have been reported to vary according to the parents' race, ethnicity and migrant status; however, such disparities are poorly understood. In this paper, the available evidence and potential clinical significance of racial/ethnic and migrant disparities in gestational length and preterm delivery are assessed alongside potential explanatory factors. Although measurement bias in gestational length has the potential to inflate disparities, there is a consistently higher risk of preterm birth among some racial/ethnic groups. These differences most likely reflect lasting socio-economic disadvantage and discrimination rather than genetic mechanisms. The effect of migrant status is less conclusive due to heterogeneity of populations and the healthy migrant effect; however, environmental influences in the receiving country are implicated in driving increases of overall preterm rates. When assessing preterm delivery rates across ethnic and migrant groups, the use of standardized, ultrasound-based pregnancy dating methods is crucial to minimize bias. Current evidence does not justify the provision of a different clinical care approach to minority or immigrant women solely based on their race, ethnicity or country of origin; however, these labels may serve as flags for further inquiry on individual risk factors and a detailed obstetric history.
Keywords: ethnicity; gestational length; migration; minority groups; preterm delivery; race.
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