This paper provides an overview of established approaches for function integration in additive manufacturing and critically compares their capabilities. One of the decisive factors is how functions and structures are addressed. This is necessary because function integration - among many others - affects material decisions and the manufacturing process chain. It is one of many reasons to rethink the product architecture and a way to support the design of resource-efficient products. Various strategies for function integration exist. However, there are currently no approaches in additive manufacturing that provide systematic support for early function integration.A systematic literature review identified 21 unique approaches. All approaches were categorized according to their abstraction level within a product architecture and their design type to be supported. They were then compared on the basis of their categorization, design objective and strategy for function integration to allow for a better understanding of when to use the approaches in research and practice. Key findings and considerations for adapting function integration approaches to early design stages are presented. In addition, several research gaps were identified.