Introduction: Though interest is growing for trials comparing planned delivery mode (vaginal delivery [VD]; cesarean section [CS]) in low-risk nulliparous women, appropriate study design is unclear. Our objective was to assess feasibility of three designs (preference trial [PCT], randomized controlled trial [RCT], partially randomized patient preference trial [PRPPT]) for a trial comparing planned delivery mode in low-risk women. Methods: A cross-sectional survey of low-risk, nulliparous pregnant women (N = 416) and healthcare providers (N = 168) providing prenatal care and/or labor/delivery services was conducted in Argentina (2 public, 2 private hospitals). Proportion of pregnant women and providers willing to participate in each design and reasons for not participating were determined. Results: Few women (< 15%) or professionals (33.3%) would participate in an RCT, though more would participate in PCTs (88% women; 65.9% professionals) or PRPPTs (44.4% public, 63.4% private sector women; 44.0% professionals). However, most women would choose vaginal delivery in the PCT and PRPPT (> 85%). Believing randomization unacceptable (RCT, PRPPT) and desiring choice of delivery mode (RCT) were women’s reasons for not participating. For providers, commonly cited reasons for not participating included unacceptability of performing CS without medical indication, difficulty obtaining informed consent, discomfort enrolling patients (all designs), and violating women’s right to choose (RCT). Conclusions for Practice: Important limitations were found for each trial design evaluated. The necessity of stronger evidence regarding delivery mode in low-risk women suggests consideration of additional designs, such as a rigorously designed cohort study or an RCT within an obstetric population with equivocal CS indications.Fil: Amyx, Melissa Michele. Instituto de Efectividad Clínica y Sanitaria; Argentina. University of Tulane; Estados UnidosFil: Althabe, Fernando. University of Tulane; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Rivo, Julie. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Pingray, María Verónica. University of Duke; Estados UnidosFil: Minckas, Nicole. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Belizán, María. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Gibbons, Luz. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Murga, Gerardo T.. Instituto de Maternidad Y Ginecología Nuestra Señora de Las Mercedes; ArgentinaFil: Fiorillo, Angel Eduardo. Centro de Educación Médica e Investigaciones Clínicas "Norberto Quirno"; ArgentinaFil: Malamud, Julio D.. Centro de Educación Medica E Invest.clinicas; ArgentinaFil: Casale, Roberto A.. Sanatorio de la Mujer.; ArgentinaFil: Cormick, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; Argentina. Hospital Nacional Profesor Alejandro Posadas; ArgentinaFil: Belizan, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; Argentina