1. Main studies characteristics.

Study	Population	Index test					Reference standard(s)
	Antenatal diagnosis of CHD	Pulse oximeter	Limb	Test timing	Oxygen saturation	Threshold	Positive pulse oximetry	Negative pulse oximetry
Arlettaz 2006	included	Nellcor NPB‐40	post‐ductal	within 24 hours	functional	< 95%	echocardiography	NA
Bakr 2005	excluded	Digioxi PO 920	pre‐ductal and post‐ductal	longer than 24 hours	fractional	≤ 94%	echocardiography	cardiology database
Bhola 2014	included	Masimo Radical 5	post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	cardiology database
De‐Wahl 2009	excluded	Radical SET v4	pre‐ductal and post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	mortality data
Ewer 2011	included	Radical‐7	pre‐ductal and post‐ductal	within 24 hours	functional	< 95%	echocardiography	clinical follow‐up, cardiology database & congenital registry
Gomez‐Rodriguez 2015	excluded	Radical‐5	post‐ductal	within 24 hours	functional	< 95%	echocardiography	clinical follow‐up
Jones 2016	excluded	NA	pre‐ductal and post‐ductal	within 24 hours	NA	≤ 95%	echocardiography	National Congenital Heart Disease Audit
Klausner 2017	excluded	NA	pre‐ductal and post‐ductal	longer than 24 hours	NA	< 95%	echocardiography	clinical follow‐up
Koppel 2003	excluded	Ohmeda Medical	post‐ductal	longer than 24 hours	functional	≤ 95%	echocardiography	clinical follow‐up & congenital registry
Meberg 2008	excluded	RAD‐5v	post‐ductal	within 24 hours	functional	< 95%	echocardiography	clinical follow‐up
Oakley 2015	excluded	Nellcor NPB 40	post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	cardiology database & mortality data
Ozalkaya 2016	excluded	Nellcor	pre‐ductal and post‐ductal	longer than 24 hours	functional	≤ 95%	echocardiography	echocardiography
Richmond 2002	included	Oxi machine	post‐ductal	within 24 hours	fractional	< 95%	echocardiography	mortality data & congenital registry
Riede 2010	excluded	NA	post‐ductal	longer than 24 hours	functional	≤ 95%	echocardiography	congenital registry
Rosati 2005	excluded	NA	post‐ductal	longer than 24 hours	functional	≤ 95%	echocardiography	clinical follow‐up
Sendelbach 2008	excluded	Nellcor N‐395	post‐ductal	within 24 hours	functional	< 96%	echocardiography	clinical follow‐up
Singh 2014	excluded	NA	pre‐ductal and post‐ductal	within 24 hours	functional	< 95%	echocardiography	mortality data & congenital registry & cardiology database
Turska 2012	excluded	Novametrix, Nellcor & Masimo	post‐ductal	within 24 hours	functional	< 95%	echocardiography	clinical follow‐up and Public Health registries
Van Niekerk 2016	excluded	Nellcor	pre‐ductal and post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	NA
Zhao 2014	excluded	RAD‐5V	pre‐ductal and post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	clinical follow‐up
Zuppa 2015	excluded	Ohmeda 3900	post‐ductal	longer than 24 hours	functional	< 95%	echocardiography	NA
NA: not available