Prenatal factors affecting intrauterine growth retardation.

Intrauterine growth retardation (IUGR), like postnatal growth retardation, involves skeletal and soft tissues. It is important to distinguish between depletion of soft tissues and stunting of linear skeletal growth, not only in older infants and children, but also in newborn infants. There are three main types of IUGR. To diagnose all three types involves much more than simply obtaining an individual's weight in relation to his or her age, as is now the widely accepted practice in newborn infants. Standards of intrauterine growth should not include growth-retarded newborn infants, insofar as it is possible to exclude them. Tables and graphs of intrauterine growth based on representative populations of newborn infants are apt to be a mixture of unknown numbers of normally grown and growth-retarded fetuses. The suggestion is put forward that standards of intrauterine growth should be based on newborn infants who have not been subjected to known growth-retarding influences prenatally. The diagnosis of intrauterine growth retardation prenatally by ultrasonic techniques has not reached the degree of reliability and validity that is needed for the routine detection of all fetuses with severe intrauterine growth retardation. Prenatal measurements made by ultrasound still require confirmation postnatally by appropriate measurements of infants at birth. The epidemiology, diagnosis, and postnatal courses of newborn infants with severe types of IUGR are discussed.