Module 1 - GAP Theory
Module 2 - GAP Practice

5.4 Antenatal detection of SGA

Antenatal detection of SGA  33 – (birth weight <10th customised centile) GAP (UK) user average 2015-2019

GAP user average detection rate has increased from baseline of 19.1% to 42%
However there is wide variation between units. The average of the ‘top ten’ rates in the country was 62% (range 58-65) in 2019.
A survey of these units has shown that they tended to have more comprehensive training and protocols for antenatal risk assessment and surveillance. 
False positive rates were encouragingly low: 7% overall, and 12.7% for the Top Ten group.


33 Gardosi J, Francis A, Turner S, Williams M. Customized growth charts: rationale, validation and clinical benefits.
Am J Obstet Gynecol. 2018;218(2). https://doi.org/10.1053/j.semperi.2003.12.002