Abstract

In recent years there has been rapidly increasing interest in babies whose birthweight is low because their intrauterine growth has been retarded, and it has been recognized that the clinical problems of these 'small-for-dates ' babies differ from those of true prematures. They rarely die from respiratory distress syndrome or intraventricular haemorrhage, but are particularly susceptible to symptomatic hypoglycaemia and intrapulmonary haemorrhage (Gruenwald, 1963; Dawkins, 1965). It is, there-fore, a matter of practical importance to know whether a particular baby of low birthweight is truly premature or small-for-dates, a distinction that depends on accurate knowledge of the gestational age. This is most accurately measured by calcula-tion from the first day of the mother's last menstrual period, provided her cycle is regular and her memory correct. Often, however, these conditions do not hold, and some independent method of assessing gestational age is required. Small-for-dates babies cannot be recognized from their general appearance which is often indistinguishable from that of true prematures (Gruenwald, 1963). Most bodily dimensions are affected by the intrauterine growth retardation. Head circumference is a possible exception, but its normal variation is such that it does not by itself give a sufficiently accurate estimate of gestational age. Epiphysial development is a poor index of maturity since it is retarded in small-for-dates babies (Scott and Usher, 1964; Wiggles-worth, 1966). It has been suggested that the best criteria of maturity are based on neurological development (Gesell and Amatruda, 1945) which is unaffected by intrauterine growth retardation (Bergstr6m,