The purpose of the study is to investigate the influence of psychosocial stress, maternal schooling, social support, psychological well-being, alcohol and smoking on intrauterine growth retardation and premature delivery. At a Copenhagen university hospital 2432 consecutive Danish-speaking women in 20th week of pregnancy completed a questionnaire including the General Health Questionnaire and Severity of Psychosocial Stressor Scale and questions about social network, education, smoking and drinking habits. In 212 cases (8.7%) the women delivered before day 259 of gestation. In a multiple logistic regression model, pre-term delivery proved to be associated with psychosocial stress and poor school education. In 152 cases (6.3%) infants had a birth weight below the defined 10th percentile. In a multiple logistic regression model, IUGR was associated with smoking. In preventive programmes, such as anti-smoking campaigns, it should be kept in mind that women who smoke are also the least educated and have the poorest support from a social network.