OBJECTIVES: This study examined whether there were significant differentials between US-born and foreign-born women in risks of infant mortality, low birthweight, and preterm birth and whether these differentials, if they existed, varied across major US racial/ethnic groups. METHODS: Multivariate logistic regression was applied to national linked birth/infant death records for 1985 through 1987 to estimate overall and ethnic-specific maternal nativity effects on pregnancy outcomes. RESULTS: Substantial maternal nativity differences in risks of infant mortality and low birthweight were found, with the magnitude of the nativity effect varying significantly across racial/ethnic groups. Overall, foreign-born status was associated with 7% and 20% lower risks of low birthweight and infant mortality, respectively. However, the reduced risk of adverse pregnancy outcome associated with immigrant status tended to be substantially larger for Blacks, Cubans, Mexicans, and Chinese than for other ethnic groups. CONCLUSIONS: Maternal nativity status, along with ethnicity, may serve as an important axis of differentiation in birth outcome studies. Further research needs to be conducted to assess the effects of behavioral, cultural, and psychosocial factors in explaining the nativity differentials observed here.