Study	Reason for exclusion
Ginsberg 1997	This study was excluded because it was a cost analysis of DL‐UVCs versus SL‐UVCs.
Pinheiro 1992	This study was excluded because it was a case series with no control group. Triple lumen catheters were inserted through umbilical vein in 13 neonates.
Ramachandran 1994	This study was excluded because it was a retrospective study. 128 neonates: 70 in SL‐UVCs group, 58 in DL‐UVCs group.
Storme 1999	This study was excluded because the treatment allocation was not random or quasi‐random. The population was divided in to two groups according to severity of respiratory failure. Group I (n = 52): normal hemodynamic parameters and moderate respiratory failure (FIO2 < 0.6), only SL‐UVC was used. Group II (n = 56): low systemic pressure requiring vascular filling and/or inotropic drug infusion, and/or severe respiratory failure (FIO2 > 0.6), in this group either SL‐UVC or DL‐UVC was used.