The three main conditions that are associated with childbirth are the maternity blues, postnatal depression and post-partum psychosis. The prevalence of the blues, which are mild, transient and very common disturbances of postnatal mood, does not appear in a major way to be related to environmental, social or cultural factors. Postnatal depression, which has a predominantly psychosocial etiology, surprisingly does not appear to vary in incidence across different cultures in the few studies reported that permit direct comparisons. There is also no good evidence for or against the theory that postnatal depression is partly the consequence of the customs and rituals that traditionally mark the transition to parenthood being stripped away in developed Western societies. However, the lack of relevant research and limitations of method severely restrict any conclusions that can be drawn. There is much firmer evidence for a consistent incidence of post-partum psychosis across cultural and ethnic divides; this observation, together with clinical data and historical evidence of an unchanging incidence rate during the past 150 years, points to a primarily endogenous etiology for the psychoses, which may be triggered by the physiology of childbirth. The transcultural approach to postnatal psychiatric disorders provides a unique opportunity not only to test hypotheses about social and cultural contributions to the etiology of psychotic and non-psychotic reactions to childbirth, but also an opportunity to study the ways in which social factors can influence the evolution of psychopathology. It is also possible that in some cultures the family and social milieu may play a major part in buffering infants from the adverse effects of maternal postnatal illness, but the evidence is anecdotal. Systematic research across cultures will lead to better recognition of maternal illness as well as to better prevention and management.