We wanted to analyze the association between small-for-gestational-age (SGA) births, defined as a newborn with a birthweight below the 15th percentile-for-gestational age, and socioeconomic and psychosocial risk factors. Information on social background, psychological status, and life events was collected prospectively by use of questionnaires in the second and third trimester of pregnancy. The respondents were 1552 women who expected their second or third child and took part in a Scandinavian multicenter study of fetal growth and perinatal outcome. No significant differences were found in relational stress, state and trait anxiety, depression, and physical strain between SGA and non-SGA births, whereas smoking around time of conception and low prepregnant body mass were significant SGA birth predictors. Maternal and paternal education of nine years or less increased the SGA birth risk (RR 1.46 (95% CL 1.12; 1.92) and RR 1.34 (95% CL 1.01; 1.79), respectively. The increased risk from a low maternal education was still significant when body mass and low paternal education were controlled, but not after adjustment for maternal smoking. A protective effect of paternal, but not maternal, education of 12 years or more was also observed and retained its effect when maternal smoking and body mass were controlled. In this seemingly homogeneous Scandinavian population, parental education and maternal body proportion and life style influenced the prevalence of small-for-gestational-age births. Relational stress, anxiety, depression, and physical strain did not influence birth outcome.