The first part of the report deals with occurrence of methylxanthines in foods, beverages, and medicines, and estimates of caffeine intake. In addition, a short review of the pharmacological and toxicological actions of caffeine is given. The second and main part of the report reviews available information from epidemiological studies on the potential health hazards to the human foetus associated with parental intake during pregnancy of caffeine and related methylxanthines in foods, beverages and medicines. The studied adverse effects are influence on fertility, spontaneous abortion, congenital malformation, pre-term delivery, foetal growth retardation, foetal behaviour and effects on neonates, infants and young children. The conclusion of the report demonstrates the need for limiting caffeine exposure during pregnancy. The Nordic Working Group on Food Toxicology and Risk Evaluation (NNT) recognizes that the human exposure to caffeine and related compounds causes a spectrum of pharmacological effects, for instance cardiovascular, renal, neurological and behavioural effects. The increasing use of caffeine and related methylxanthines in various foods and beverages consumed by children and adolescents cause concern. NNT recommends that a full hazard characterization of caffeine and related methylxanthines should be performed with the aim to reach a conclusion about the upper safe level of intake of these compounds.