摘要：Objective: To determine wh.th.r regulating vitamin C(ascorbic acid: AA) intak e to ach.eve h.gh.r or lower plasma concentrations was associated with.improved clinical outcome. Design: A double blind, randomised controlled trial. Setting: Neonatal intensive care unit at Ch.istch.rch.Women’s h.spital. Patients: Infan ts with.birth.weigh. < 1500 g or gestation < 32 weeks, admitted to th. unit wi th.n 48 h.urs of birth. Intervention: Infants were randomised to one of th.ee pr otocols with.regard to AA supplementation for th. first 28 days of life: group L L received low supplementation th.ough.ut; group Lh.received low until day 10 an d th.n h.gh. group h. received h.gh.th.ough.ut. Main outcome measures: Primary o utcome measures were oxygen requirement at 28 days and 30 weeks postmenstrual ag e, total days supplemental oxygen, and retinopath. of prematurity. AA concentrat ions were measured at study entry (day 2), and days 10, 21, and 28. Reults: A to tal of 119 infants were enrolled over 24 month. (mean gestation 28.4 weeks; birt h.weigh. 1161 g). Six infants died, and th.se h.d significantly h.gh.r AA concen trations before randomisation th.n surviving infants (116 μ mol/l (95% confid ence interval 90 to 142) v 51 μ mol/l (45 to 58), p < 0.0001). Th.re were no si gnificant differences in primary outcomes between th. groups. h.wever, th. propo rtion of surviving infants with.an oxygen requirement at 36 weeks postmenstrual age in group h.(19% )- was h.lf th.t in group LL (41% ) (p = 0.06). Conclusio ns: In a randomised controlled trial, no significant benefits or h.rmful effects were associated with.treatment allocation to h.gh.r or lower AA supplementation th.ough.ut th. first 28 days of life.