AbstractPurposeWe investigated factors associated with maternal consent to use residual newborn dried bloodspots (DBS) in a national case–control study of birth defects.MethodsA subset of sites in the National Birth Defects Prevention Study (NBDPS; 1997–2011) asked participants to provide consent for investigators to retrieve DBS from local newborn screening programs to use for research on risk factors for birth defects. We assessed whether consent differed by factors including maternal age, education, parity, body mass index, language of interview, country of birth, and case–control status.ResultsOf 5,850 mothers of cases and 2,534 mothers of controls, 57% provided consent for the DBS component. Mothers of cases were more likely to participate than mothers of controls (61% vs. 52%), as were mothers who self‐reported white race, >12 years of education, and born in the United States.ConclusionsRetrieval of DBS can be integrated into retrospective studies of neonatal outcomes including birth defects. In NBDPS, participation in the DBS component was moderate and varied by some sociodemographic factors. Further research is needed to better understand families' perspectives on using residual DBS for secondary research. Representative participation is important to reduce the potential for selection bias in future studies using DBS for children's health research.