Purpose: To determine the independent effects of maternal age and race/ethnicity on poor pregnancy outcomes, with and without controlling for other factors. Methods: Logistic regression analysis of 54,447 linked birth, fetal death, and infant death certificates in California from 1980-87. Results: Women of young maternal age (10-13 years) are approximately 2.5 times more likely to have a low birthweight infant and 3.4 times more likely to have a preterm birth than women of ''prime'' childbearing age. African-American women are 1.7 times more likely to have a low birthweight infant, and 2 times more likely to have a preterm birth than their white and Hispanic counterparts. The association of infant death with maternal age and race/ethnicity is statistically significant in the unadjusted models, however, those associations disappear completely when birthweight and gestational age are considered. Interactions between maternal age and race/ethnicity explained very little of the variability for any of the outcomes. Conclusions: Maternal age at delivery and race/ethnicity are independently and significantly associated with pool pregnancy outcomes such as low birthweight and premature births. However, young maternal age and race/ethnicity do not appear to interact in a manner that produces a differential effect on the birth outcomes assessed in this study. The incidence of infant mortality is unrelated to maternal age or race/ethnicity, after controlling for prematurity and low birthweight, underscoring the importance of intervention efforts aimed at their prevention. (C) Society for Adolescent Medicine, 1997.