Summary.This study compares the maternal sociodemographic and prenatal care characteristics and birth outcomes of US resident white and Japanese‐American mothers, using data from the state of Hawaii. The specific focus is to determine to what extent these factors can explain variations in newborn maturity and mortality indicators. Single livebirths to resident, non‐military dependent white and Japanese‐American mothers were selected for analysis from the 1979–1990 linked livebirth‐infant death files from Hawaii. Compared with white mothers, Japanese‐American mothers were significantly more likely to be married, age 18 years and older, have higher educational attainment, and have adequate prenatal care utilisation. The majority of Japanese‐American mothers were born in Hawaii, while the majority of white mothers were born on the US mainland. The mean birthweight of Japanese‐American infants was 200 g lighter than that of white infants. Infant mortality rates (IMRs) for both groups were below the US Year 2000 Health Objective. After controlling for maternal sociodemographic and prenatal care factors with logistic regression, Japanese‐American infants had significantly higher risks of low birthweight, preterm and very preterm birth and of being small‐for‐gestational age. These findings indicate that populations with preferential maternal sociodemographic and prenatal care risk indicators may still exhibit higher low birthweight percentages, but achieve c