“…A relatively large proportion of autosomal trisomies in spontaneous abortions apparently involve a chromosome of the G group, and it has been suggested that the mother's age may influence the rejection of G-trisomic embryos (Polani, 1966). Controlled studies of the pattern of fertility in the mothers of mongol children have been few; but generally speaking later work (Smith and Record, 1955;Lunn, 1959;Sigler, et al, 1967) reports findings which suggest that the previously widely held view, that the fertility of the mothers of mongols is impaired, should be questioned more closely. It does seem to be well established that the majority of such mothers, perhaps mainly that group which have produced the mongol child at an advanced maternal age (Cowie and Slater, 1963), have more than the expected number of miscarriages; but, obviously, this may have only the slightest or no infiuence on the total number of children born alive in the course of a reproductive lifetime.…”