The objective is to analyze the variation of obstetric and gynecological factors into heritable and non-heritable components. The completed Record Linkage files have been used to estimate genetic components in obstetric variables, both continuous and discrete: age at menarche, lengths of stages of labor, gestation time, diagonal conjugate, anemia, toxemia, albuminuria, hemorrhage, abnormal presentation, abruptio placentae, fetal death and nine others. A quite substantial paper, which seems to be the first systematic discussion based on directly relevant data, has been published.