The aim of this guideline is to make recommendations regarding the diagnosis and management of small-for-gestational-age (SGA) fetuses. It does not address multiple pregnancies or pregnancies with fetal abnormalities.
SGA refers to a fetus that has failed to achieve a specific biometric or estimated weight threshold by a specific gestational age. Various thresholds (2.5th, 3rd, 5th, 10th, 15th and 25th centiles and 1.0, 1.5 or
2.0 standard deviations below the population average) are used for various fetal measures. The commonly used threshold is the tenth centile for abdominal circumference and estimated birthweight. SGA fetuses are a heterogeneous group comprising fetuses that have failed to achieve their growth potential (fetal growth restriction, FGR) and fetuses that are constitutionally small. Approximately 50–70% of fetuses with a birthweight below tenth centile for gestational age are constitutionally small, and the lower the centile for defining SGA, the higher the likelihood of FGR. On the other hand, a fetus with growth restriction may not be SGA. SGA fetuses are at greater risk of stillbirth, birth hypoxia, neonatal complications impaired
neurodevelopment and possibly type 2 (non-insulin-dependent) diabetes and hypertension in adult life. The reason that studies on SGA fetuses have shown poor perinatal outcome is likely to be the high incidence of true FGR in this group. However, the vast majority of term SGA infants have no appreciable morbidity or mortality.
This guideline can be downloaded as a pdf using the link below.
