“…Most studies were conducted in the USA [14, 23-27, 31, 32, 34] while the remainder were based in India [28,33], United Kingdom [29], China [35] and Taiwan [30]. Half of the studies used national or regional health system or insurance databases [14, 23-25, 27, 29, 30] and others used either multiple [31,32,34] or single hospitals. [26,28,33,35] Populations of 34-36 [14,27,29,[32][33][34]]/33-36 week GA babies [24] were most frequently studied, followed by < 37 weeks GA [23,25,26,30,35], 28-36 weeks GA [30] and VLBW [31].…”