“…Again, variable definitions of BPD were used. The majority of studies (n = 26) used case-control study design (18,19,22,23,25,28,29,32,34,35,37,39,41,42,44,45,54,56,59,62,63,66,67,70,71,75), and the remaining used either retrospective (n = 4) or prospective (n = 4) cohort study designs (20,24,36,43,49,52,57,60).…”