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Small-for-Gestational-Age Fetus, Investigation and Management (Green-top Guideline No. 31)

Published: 22/03/2013

This is the second edition of this guideline. It is a major update of the first edition, which was published in 2002 under the same title.


Update December 2014: New evidence and guidance in this field were reviewed in 2014 and it was decided that revision of this guideline would be deferred to a later date. The version available on the website and app will remain valid until replaced.


Small-for-gestational age (SGA) refers to an infant born with a birth weight less than the 10th centile. Small fetuses are divided into normal (constitutionally) small, non–placenta-mediated growth restriction (for example: structural or chromosomal anomaly, inborn errors of metabolism and fetal infection) and placenta mediated growth restriction.

Maternal factors can affect placental transfer of nutrients, for example low prepregnancy weight, undernutrition, substance abuse or severe anaemia. Medical conditions can affect placental implantation and vasculature and hence transfer, for example pre-eclampsia, autoimmune disease, thrombophilias, renal disease, diabetes and essential hypertension.

The purpose of this guideline is to provide advice that is based on the best evidence where available to guide clinicians regarding the investigation and management of the SGA fetus. It reviews the risk factors for an SGA fetus and provides recommendations regarding screening, diagnosis and management, including fetal monitoring and delivery. This guideline does not address multiple pregnancies or pregnancies with fetal abnormalities.