Primary health care services are responsible for preventive measures to optimize child development in the first years of life. In Denmark, these services are shared between general practitioners and municipality health visitors. National guidelines mandate collaboration between these professionals but in reality, they work in parallel. We aimed to explore how professionals experience collaboration and communication regarding children with professional concern about their wellbeing. Seventeen semi-structured interviews were conducted with general practitioners, and health visitors. Both professions considered closer collaboration to be important in meeting children’s needs. Barriers to collaboration and communication included differing legal obligations, Information Technology-systems (IT), lack of financial incentives, lack of mutual professional acknowledgment and respect, and absence of routines for sharing knowledge. The traditional division of responsibilities between physicians and nurses in which all professionals involved in preventive child health care are acculturated seems to impede collaboration based on unequal professional status. IT infrastructure needs to support information sharing and structures to support informal meetings between professionals are warranted to support more collaborative practice.