Our Swedish population‐based cerebral palsy (CP) project started 25 years ago and today covers the birth years 1954–1990, with over 1400 CP cases. This large series (1, 2, 3) has opened new perspectives on time trends and aetiological background factors, where two areas of successively increasing knowledge stand out as particularly helpful. One is the growing amount of biological and clinical data from the continuously increasing cohorts of surviving very preterm infants, the other is the rapidly expanding and refined information from neuroimaging. Bilateral spastic CP (BSCP), including spastic and ataxic diplegia, tetraplegia and spastic‐dyskinetic CP, is the most prevalent clinical group of CP syndromes, present in around 75% of preterm and 45% of term CP, and has shown the most significant prevalence changes over time. In this presentation we, therefore, focus on BSCP, also analysed in a collaborative study between southwest Germany and western Sweden and recently presented in a series of four papers (4, 5, 6, 7).