Background: To study causal associations between factors occurring during pregnancy, birth, and infancy and global quality of life (QOL) in adulthood 31-33 years later. Material/Methods: Prospective study from the Copenhagen Perinatal Birth Cohort 1959-61. Two sets of questionnaires, one filled out by physicians during pregnancy, birth, and infancy and a validated, self-administered questionnaire on global quality of life (QOL) filled out by the person 31-33 years later (7,222 people). Results: Only a few of the factors examined showed association with later QOL. Regarding the mothers, associations were found between global QOL and mothers with congenital malformations (8.8%) or syphilis (8.5%), failing contraception (3.8%), and low social group (6.9%). Two main factors in pregnancy associated with reduced QOL for the child 31-33 years later: the mother's smoking habits (2.7%) and her medication, especially painkillers (15.3%) and different psychotropic drugs, with the association most prevalent early in pregnancy. Most of the associations found involved factors during the child's first year, including the mother's attitude towards her pregnancy (3.4%), unsuccessful abortions (2.2%), institutionalization (7.4%), meningitis (11.7%), and psychomotor development (14.2%). Conclusions: The results appear to disagree with previous reports that factors occurring during pregnancy, birth, and infancy are highly important for the later quality of life of the adult child. In accordance with other studies, this suggests that the aspects important for quality of life are influenced only to a minor degree by earlier conditions, but the major aspects are dependent on later attitudes towards life and philosophy of life.