Table 1

Description of included studies

Study	Gestation	Sample size	Symptomatic/asymptomatic	Packed cell volume	Planned reduction	Mode of exchange	Short term follow up assessment	Long term follow up assessment
PCV, Packed cell volume; BNBAS, Brazelton neonatal behavioural assessment scale; BSID, Bayley scales of infant development; WRAT, wide range achievement test.
Van der Elst et al¹⁰	Not clearly stated	49	No distinction made between symptomatic/asymptomatic. All symptoms considered minor	PCV of 65%	PCV to <60%	Umbilical vein catheter. FFP	BNBAS and neurological assessment of Prechtl at 10 days	Neurological, developmental assessment at 8 months (similar to the Griffith development score)
Goldberg et al¹¹	Not clearly stated	20	No distinction made between symptomatic and asymptomatic	Venous PCV ⩾64% and hyperviscous. Antecubital vein	PCV to 50%	Umbilical vein catheter. FFP	BNBAS at 8 h, 24 h, 72 h, and 2 weeks	BSID and neurological assessment at 8 months
Black et al¹²	“Term”	93	No distinction made between symptomatic and asymptomatic	Venous PCV 65% and hyperviscous. Antecubital vein	PCV to 50%	Umbilical vein catheter. FFP	Neonatal symptoms	BSID and neurological assessment at 1 and 2 years. Slosson IQ and WRAT test at 7 years
Bada et al¹³	Not clearly stated	28	Only asymptomatic patients were randomised	Radial artery PCV ⩾63%	PCV to 55%	Route not stated. Plasmanate	Cerebral artery Doppler measurements	BSID or Stanford Binet and neurological assessment at 30 months
Ratrisawadi et al¹⁴	Not clearly stated	105	Only asymptomatic patients were randomised	Central venous PCV 65% or more	PCV to 60%	Route not stated	None	Gasel development at 1.5–2 years