This paper provides an estimate of the prevalence of subfecundity and spontaneous abortion in Denmark, and examines social factors associated with these problems of reproduction. The data of this study were collected by interviewing a stratified random sample of 1.4 women per thousand in Denmark between the ages 25 and 45. The interview generated detailed information on reproductive history and sociodemographic data for 709 women. The survey results indicate that reduced fecundity is a relatively common health problem. The proportion of women that either could not achieve a wanted conception or experienced a delay of one or more years before achieving conception was 0.16 in a first pregnancy and 0.17 in a second or subsequent pregnancy attempt. Four per cent of the women interviewed never produced a desired first child and an additional four per cent reported failure to produce a second or subsequent desired child. Social factors relating to subfecundity and spontaneous abortion were studied using logistic regression. No significant associations were found between the occurrence of subfecundity and family net income, employment status of the 'head of the household', area of residence, type of housing or age at time of interview. Women without a college education were more likely to exhibit primary subfecundity than college-educated women (p less than .05). The rate of spontaneous abortion was not found to be associated with socioeconomic class. A significantly higher rate of abortion was found among women with a history of subfecundity than among women with no such history.