All cases of spontaneous abortion which were registered between June 1982 and June 1984 in the Ciudad Sanitaria de la Paz have been studied in Madrid (n = 1,259). Together with the women who had miscarriages, a control sample of women (n = 1,016) of similar socioeconomic status and ages was analyzed. The main aim of this study is the analysis of the link between the age of menarche and the incidence of miscarriage, as well as morphological characteristics of women. Our results demonstrate that the average age of menarche is earlier in the sample of women who have a miscarriage (P > .001). When women are classified by early, middle, or late age at menarche, it was observed that, for the sample of women who had a miscarriage, there is a higher percentage of both early and late age at menarche. No significant differences were found in the rest of the morphological variables which were considered. The cycles of women who had miscarriages were more irregular than those in the control group.