OBJECTIVE: Discrepancies between cfDNA and ultrasound predicted fetal sex occur, possibly indicating disorders/differences of sex development (DSDs). Among expectant/recent parents, this study assessed: cfDNA knowledge/use, fetal sex determination attitudes/behaviors, general knowledge of DSD, and possible psychological impact of discrepancy between fetal sex on cfDNA and ultrasound. METHOD: Parents were surveyed about fetal sex determination methods, knowledge of cfDNA and DSD, distress related to possible cfDNA inaccuracy. RESULTS: Of 916 respondents, 44% were aware of possible discrepancy between cfDNA and ultrasound, 22% were aware of DSD. 78% and 75% would be upset and worried, respectively, with results showing fetal sex discrepancy. Most (67%) revealed predicted fetal sex before delivery. 38% were offered cfDNA. Of those revealing fetal sex, 24% used cfDNA results, 71% ultrasound, and 7% both. cfDNA users were more frequently aware of possible discrepancy between cfDNA and ultrasound (76% vs 41%, P < 0.0001), but not of DSD (29% vs 23%, P = 0.29). CONCLUSION: Fetal sex determination is favored, and cfDNA is frequently used for predicting fetal chromosomal sex. Many parents are unaware of possible discrepancies between cfDNA and ultrasound, and potential for DSD. Most would be distressed by discordant results. Accurate counseling regarding limitations cfDNA for fetal sex determination is needed. This article is protected by copyright. All rights reserved.