Background: Lifestyle, in particular obesity and smoking has significant impacts on fertility and an important focus for the treatment of reproductive failures is the optimisation of periconceptional lifestyle behaviours. The preimplantation intrauterine environment within the uterus is also key for embryo development and early programming. Although the benefits a healthy periconceptional lifestyle are well described, there remains a paucity of data demonstrating the efficacy of interventions designed to optimise preconceptional lifestyle behaviours and choices. Methods: This study is a prospective randomised controlled trial which aims to address the question of whether an online personalised lifestyle coaching application is an effective means of delivering periconceptional advice in women suffering from reproductive failures. Women suffering from subfertility or recurrent miscarriages attending the outpatient clinic will be randomised into either the intervention arm (personalised online lifestyle coaching application) or the control arm (standard periconceptional advice including information from NHS websites). Both groups will be asked to complete a validated lifestyle questionnaire at baseline, and 6, 12, 18 and 24 weeks after randomisation. The primary outcome is the composite dietary and lifestyle risk score at 12 weeks. The secondary outcomes will include compliance with the program, proportion achieving spontaneous conception during the study period and the dietary and lifestyle risk score at 24 weeks. Discussion: With this study, we aim to clarify whether a personalised online based lifestyle coaching application is more effective at improving behaviours than standard advice offered by National Health Service (NHS) resources. A personalised lifestyle coaching application may represent an empowering and cost effective means of delivering periconceptional advice in women with subfertility or recurrent miscarriages. Trial registration: The iPLAN trial was retrospectively registered (ISRCTN 89523555).