Objective: This study aimed to examine the association between maternal pre-pregnancy underweight and the risk of small-forgestational-age (SGA) birth among Asian Americans compared with non-Hispanic (NH) whites. Methods: Using 2014-2018 birth data, we categorized maternal underweight and SGA according to severity. Bivariate analyses were performed to examine the demographics and maternal body mass index (BMI). Adjusted logistic regression models were used to analyze the association between maternal BMI and SGA among Asian Americans compared with NH-Whites. Results: In Asian Americans, the likelihood of SGA birth was higher among underweight mothers than among mothers with a normal BMI (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.30-1.46). We observed that as the severity of maternal underweight increased, the adjusted odds of SGA increased. Underweight Asian American mothers were more likely to give birth to SGA infants than underweight NH-White mothers (OR, 1.36; 95% CI, 1.28-1.44). Conclusion This study shows the association between maternal underweight and SGA birth among Asian Americans, supporting the development of culture-sensitive interventions addressing the impact of weight on pregnancy.