[Obstetric complications and risk of schizophrenia. An association appears undisputed, yet mechanisms are still unknown].

This paper reviews the literature on obstetric complications (e.g. premature births and hypoxia at birth) and the later development of schizophrenia. Some forty studies and two meta-analyses are summarised concerning methods and results. The balance of evidence today supports an association between obstetric complications at different points of time: during foetal life, delivery, as well as during neonatal life. This is supported by other studies of early life risk factors, e.g. infections, maternal stress and famine. Presuming there is a causal relationship, the results may support the view that various underlying "mechanisms" may be associated with schizophrenia. On the other hand this does not exclude a final common pathway. One candidate, among others, is the deleterious effects of hypoxia, hypoglycaemia, and hyperbilirubinaemia on the NMDA-receptors. To further understand how the factors are related, the statistical models in epidemiological research have to be improved and co-operation with other disciplines such as neuropathology and genetics is a necessity.