INTRODUCTION. Development in infancy and early childhood affects mental and physical health later in life. Maternal mental health and attachment between mother and child are important for a healthy development. This qualitative study explored first-time mothers’ experiences with a web-based intervention aimed at improving maternal mentalisation skills and mental health, thereby affecting child development. METHODS. Twelve first-time mothers were interviewed about their experiences using the website. RESULTS. During pregnancy, the mothers were positive towards using the web-intervention to find information and support for emotional challenges related to the transition to motherhood. However, the interest decreased after giving birth. The mothers requested a website that covered both physical and mental aspects of motherhood and provided a possibility for mothers to exchange experiences to normalise challenges. Moreover, they wanted the website to be easily accessible on a smartphone. CONCLUSION. First-time mothers experienced a need for emotional support during their transition to motherhood and were positive towards using online solutions to obtain this support. In order to be integrated into mothers’ everyday life, the intervention should be an ‘all-in-one’ solution, covering both physical and mental aspects of motherhood and infancy, include a chat forum and be easily accessible by smartphone app. FUNDING. TRYG Foundation and KEU, Capital Region of Denmark.