Perinatal stroke causes most unilateral cerebral palsy and leads to lifelong neurological disability for millions. Strong indirect evidence suggests placental thromboembolism is the most common cause of perinatal arterial ischemic stroke. As many newborns with stroke only develop symptoms days or months after the stroke occurs, acquiring placental tissue for pathological examination is challenging. However, combining such tissue pathology with rapidly advancing clinical, imaging, genetic and other biomarkers is essential if the pathophysiology of perinatal stroke is ever to be elucidated. Such progress is required if prevention strategies are ever to be realized. Fortunately, highly integrated research networks are well established in the world of perinatal stroke. These include the International Pediatric Stroke Study (IPSS) and International Pediatric Stroke Organization (IPSO) that have brought together hundreds of multidisciplinary investigators across >50 countries to enrol thousands of patients and fund large multi-centre studies and trials. Partnership between these groups and the Human Placenta Project has high potential to develop and execute the innovative studies required to define the leading mechanisms of perinatal stroke.