IMPORTANCE: Research clearly indicates that current approaches to newborn blood spot screening (NBS) education are ineffective. Incorporating NBS education into prenatal care is broadly supported by lay and professional opinion. OBJECTIVE: To determine the efficacy and effect of prenatal education about newborn screening and use of residual dried blood spots (DBS) in research on parental knowledge, attitudes, and behaviors. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial of prenatal educational interventions, with outcomes measured by survey at 2 to 4 weeks postpartum. Participants were recruited from obstetric clinics in Salt Lake City, Utah; San Francisco, California; and the Bronx, New York. Eligible women were English- or Spanish-speaking adults and did not have a high-risk pregnancy. A total of 901 women were enrolled. Participants who completed the follow-up survey included 212 women in the usual care group (70% retention), 231 in the NBS group (77% retention), and 221 women in the NBS + DBS group (75% retention). Those who completed the survey were similar across the 3 groups with respect to age, ethnicity, race, education, marital status, income, obstetric history, and language. INTERVENTIONS: Participants were randomized into 1 of 3 groups: usual care (n = 305), those viewing an NBS movie and brochure (n = 300), and those viewing both the NBS and DBS movies and brochures (n = 296). MAIN OUTCOMES AND MEASURES: Two to four weeks postpartum, women completed a 91-item survey by telephone, addressing knowledge, attitudes, and behavior with respect to opting out of NBS or DBS for their child. RESULTS: A total of 901 women (mean age, 31 years) were randomized and 664 completed the follow-up survey. The total correct responses on the knowledge instrument in regard to NBS were 69% in the usual care group, 79% in the NBS group, and 75% in the NBS + DBS group, a significant between-group difference (P < .05). Although all groups showed strong support for NBS, the percentage of women who were “very supportive” was highest in the NBS group (94%), followed by the NBS + DBS group (86%) and was lowest in the usual care group (73%) (P < .001). The interventions were not associated with decisions to decline newborn screening or withdraw residual DBS. Nine women stated that they had declined NBS (all the usual care group; P < .001). With respect to DBS, 5 participants indicated that they contacted the health department to have their child’s sample withdrawn after testing: 3 in the NBS + DBS group and 2 in the usual care group (P = .25). CONCLUSIONS AND RELEVANCE: Educational interventions can be implemented in the prenatal clinic, using multimedia tools and electronic platforms. Prenatal education is effective in increasing postnatal knowledge and support for these programs. These results are relevant to other contexts in which residual clinical specimens and data are used for research purposes. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02676245