Study	Reason for exclusion
Birch 2010	Timing of intervention (at a mean age > 2 days of life) beyond the review's inclusion criteria (i.e. heparin started within 24 hours of life).
Brown 1999	Gestational age (mean 36 weeks and 5 days) greater than that specified in the review's inclusion criteria (i.e. < 32 weeks).
Kamala 2002	Timing of intervention (at a mean age > 3 days of life) beyond the review's inclusion criteria (i.e. heparin started within 24 hours of life).
Treas 1992	Timing of intervention beyond the review's inclusion criteria; Gestational age range: 28 to 43 weeks.