Early life is an important window of opportunity to improve health across the full lifecycle. European pregnancy and child cohort studies together offer an unique opportunity to identify a wide range of early life stressors linked with individual biological, developmental and health trajectory variations, and to the onset and evolution of non-communicable diseases. LIFECYCLE will establish the EuroCHILD Cohort Network, which brings together existing, successful pregnancy and child cohorts and biobanks, by developing a governance structure taking account of national and European ethical, legal and societal implications, a shared data-management platform and data-harmonization strategies. LIFECYCLE will enrich this EuroCHILD Cohort Network by generating new integrated data on early life stressors related to socio-economic, migration, urban environment and life-style determinants, and will capitalize on these data by performing hypothesis-driven research on early life stressors influencing cardio-metabolic, respiratory and mental health trajectories during the full lifecycle, and the underlying epigenetic mechanisms. LIFECYCLE will translate these results into recommendations for targeted strategies and personalized prediction models to improve health trajectories for current and future Europeans generations by optimizing their earliest phase of life. To strengthen this long-term collaboration, LIFECYCLE will organize yearly international meetings open to pregnancy and child cohort researchers, introduce a Fellowship Training Programme for exchange of junior researchers between European pregnancy or child cohorts, and develop e-learning modules for researchers performing life-course health studies. Ultimately, LIFECYCLE will lead to a unique sustainable EuroCHILD Cohort Network, and provide recommendations for targeted prevention strategies by identification of novel markers of early life stressors related to health trajectories throughout the lifecycle.