Abstract Background: We examined birth defects in offspring of adolescent and young adult (AYA) women with a history of cancer (age 15–39 years at diagnosis). Methods: We identified AYA women diagnosed with cancer between January 1, 1999, and December 31, 2015 using population-based data from the Texas Cancer Registry; data were linked with live birth and fetal death certificates through December 31, 2016 to identify singleton births to AYA women after diagnosis. Birth defects in offspring through age 12 months were ascertained from the Texas Birth Defects Registry. We estimated risk of birth defects in offspring of AYA women and women without cancer (matched 3:1 by maternal race/ethnicity, maternal age, and offspring year of birth) and compared risk using log binomial regression models. Results: There were 6,882 singleton births to AYA women after diagnosis. Common cancer types were thyroid (28.9%), lymphoma (12.5%), and breast (10.7%). Risk of any birth defect was higher in offspring of AYA women (6.0%) compared with offspring of women without cancer [n = 20,646; 4.8%; risk ratio (RR) 1.24; 95% confidence interval (CI), 1.11–1.38]. Risk of eye or ear (RR, 1.39; 95% CI, 1.03–1.90), heart and circulatory (RR, 1.32; 95% CI, 1.09–1.60), genitourinary (RR, 1.38; 95% CI, 1.12–1.69), and musculoskeletal (RR, 1.37; 95% CI, 1.13–1.66) defects was also higher. Conclusions: Risk of birth defects was elevated in liveborn and stillborn offspring of AYA women. Impact: Although birth defects are rare, AYA women making decisions about pregnancy and prenatal care should receive appropriate counseling and surveillance.