Epidemiologic studies about preterm delivery have established several risk factors related to medical, obstetrical, socioeconomic and environmental characteristics but these factors cannot provide an explanation for up to 50% of the premature births. The influence of psychological factors has been suggested and analyzed in various studies. The present paper reviews the main data available from the literature. First, case reports and descriptive studies have confirmed that psychological factors could play a role in some women who gave birth before term. Then, many retrospective studies (conducted after delivery) have shown that the main psychological factors found among patients presenting with preterm delivery were: the number of stressful life events, the anxiety level, the maternal psychological attitude towards pregnancy, the support from partner and friends and the psychological maturity of the mother. However, a retrospective study can be biased by "effort after meaning" indicating that the experience of labour and the outcome of pregnancy could have influenced the report of the antepartum feelings. Finally, few authors have conducted prospective studies and they have reached contradictory conclusions. Newton has described a relationship between preterm delivery and the number of major life events but Stein did not confirm such association. Besides, these studies did not take into account all the medical obstetrical factors wellknown to predispose to preterm labour. Future research should involve large collaborative prospective studies assessing psychological factors through an objective method (test, questionnaire, ...) and measuring all the medical, socioeconomic and occupational characteristics in order to determine the relative role played by each of these factors in the etiopathogenesis of premature delivery.