Comparison between a normal two-day-old baby (right) with two low birthweight
babies (left and centre). The baby on the left was born nine weeks pre-term;
the baby in the centre was born full term but weighed only 1000 g.
Science Photo Library. Enlarge
Small-for-gestational age (SGA) refers to a fetus with a birth weight less than the 10th centile. SGA birth is defined as an estimated fetal weight (EFW) or abdominal circumference (AC) less than the 10th centile and severe SGA as an EFW or AC less than the 3rd centile. Some growth restricted fetuses/infants are SGA while 50-70% of SGA fetuses are constitutionally small, with fetal growth appropriate for maternal size and other important factors such as ethnicity.
Fetal Growth Restriction refers to failure of the fetus to achieve its predetermined growth potential for various reasons.
Low birth weight (LBW) refers to an infant with a birth weight < 2500 g. Fetuses with fetal growth restriction (FGR) greatly contribute to perinatal mortality and short- and long-term morbidity. There is a 3-10 fold increase in perinatal mortality in pregnancies complicated by this FGR. Therefore, identification and differentiation of potentially growth restricted fetuses (small and unhealthy) from the 'small and healthy' fetus presents a massive challenge in obstetric practice.
By the end of this tutorial you should, in respect of FGR, be able to:
Last updated: 09/02/14 (one new single best answer question added as final assessment 1)
19/06/13 (tutorial reviewed and updated by Dr Uma Rajesh)
15/12/09 (tutorial reviewed and updated by Professor Gary Mires)
19/11/09 (Full text PDF of Romo et al 2009 added to the Preliminary reading page)