Statistics
Differences in plasma kinetics or metabolic rates between these choline derivatives in preterm infants were unknown prior to the start of the study. Calculation of sample size was therefore based on plasma choline levels of preterm infants with and without choline supplementation. Plasma-free choline levels were 18.4 ± 4.8 µmol/L without and 37.7 ± 11.0 µmol/L with 30 mg/kg/d choline (choline chloride) supplementation for 10 days [Statistical and graphical analyses were done using JMP 14 (SAS Institute GmbH, Germany), and Excel 2010 (Microsoft Corporation, USA). Normal distribution was tested with Shapiro–Wilk test. Because several parameters were not normally distributed, results are shown as median with 25th and 75th percentile and non-parametric tests (Wilcoxon test) were used for between supplement comparisons.A significance level of 