Introduction: Group Antenatal Care (GANC) is an alternative for traditional antenatal care. Despite the model is well accepted among participants and is associated with positive effects on pregnancy outcomes, recruitment of participants can be an ongoing challenge, depending on the structure and financing of the wider health system. This is especially the case for primary care organizations offering GANC, which depend on other health care providers to refer potential participants. The main objective of this study is to understand what determinants are at play for health care providers to refer to GANC facilitators in primary care organizations. Accordingly, we make recommendations for strategies in order to increase the influx of women in GANC. Methods: Qualitative findings were obtained from 31 interviews with healthcare providers responsible for the referral of women to the GANC facilitators working in primary care organizations, GANC facilitators and stakeholders indirectly involved in the referral. The domains of the Consolidated Framework for Implementation Research (CFIR) and the Theoretical Domains Framework (TDF) helped to develop interview questions and raise awareness of important elements during interviews and thematic analyses. Results: The findings show that before health care providers decide to refer women, they undergo a complex process that is influenced by characteristics of the potential referrer, GANC facilitator, woman, professional relationship between the potential referrer and the GANC facilitator, organization and broader context. Discussion: Based on these findings and current literature, we recommend that the GANC team implements strategies that anticipate relevant determinants: identify and select potential referrers based on their likelihood to refer, select champions, invest in communication , concretise the collaboration, provide practical tools, involve in policymaking. ; Funding This work was supported by the National Institute for Health and Disability (CGV 2018/363). This ...