Fetal growth retardation: methods of detection

Abstract

There should be little doubt in most obstetricians’ minds that intrauterine growth retardation and smallfor-gestational-age are two different but overlapping clinical entities. The term intrauterine growth retardation (IUGR) implies failure to achieve genetic growth potential through lack of nutritional support during intrauterine life. It is widely accepted that this pathological condition is associated with an increase in perinatal mortality, neonatal morbidity and subsequent impaired neurological development including cerebral palsy. The classical picture at birth includes increased body length in relation to weight, the impression of a relatively large head with wide skull sutures, muscle wasting, prominent ribs, an alert look and a dry, wrinkled skin. However, very few infants will show all of these features. The heterogeneity of aetiological factors and clinical manifestations has led to the description of various, often poorly defined forms and types of IUGR.’ It would seem logical to use the term IUGR only when there is the clear antenatal evidence that growth has faltered, or evidence pointing to loss of fetal weight in utero.’ Small-for-gestational age (SGA), on the other hand, is a statistical concept. The 10th birthweight percentile is the most commonly used cut-off definition, but others have been applied, such as birthweight below the 5th or 3rd percentiles, or more than two standard deviations below the mean birthweight for a given gestational age. The same principle can be applied antenatally. Estimated fetal weight, abdominal circumference, fetal ponderal index or any other parameter assessing fetal size can