The Czech ELSPAC study was set up as a part of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC). ELSPAC was designed as a population-based prospective longitudinal birth cohort study to investigate the effects of biological, psychosocial, economic and environmental factors on pregnancy, delivery and subsequent child´s development and health. The study was initiated by the World Health Organization (WHO) Regional Office for Europe in 1985, with the aim to enrol 40 000 children across Europe. Seven independent centres—ALSPAC, Isle of Man, the Czech Republic, Slovakia, Ukraine, Greece and Russia—joined the project, coordinated by Professor Golding at Bristol University, UK. The coordination centre was also responsible for most of the protocol development, including follow-up planning and questionnaire design. Enrolment of the Czech participants started in 1991. In addition to the primary aims of ELSPAC, the Czech team was interested also in the effects of the profound socioeconomic changes related to the societal transformation after the fall of Communism in 1989.