Blood spots samples were extracted by adapting a protocol described previously [6]. Bloods/analytes were placed in the wells of glass coated 2.4 ml deep well plate and added with 100 μl of MilliQ H2O, 250 μl of methanol, and 500 μl of methyl tertiary butyl ether to partition the lipids. The plates were then centrifuged for 10 minutes at 6,000 rpm after being shaken for 10 minutes at 600 rpm. The organic layer on top of the aqueous phase was transferred, dried down, reconstituted, and used for lipid analysis by direct infusion high-resolution untargeted mass spectrometry (HRMS), as previously described [6,15]. Additional lipid identification was done by LC-MS/MS. Selected masses were isolated, and all spectra were recorded [6]. Only the signals of (CE(16:1), CE(16:0), PC(32:1), PC(32:0) PC(38:4), PC(38:3) TG(54:4), TG(54:3), PC(36:3), PC(36:2), TG(50:3) and TG(50:2) were used to calculate the desaturase activities yielding 6 values of lipid ratios (Table 3).

Regression models associating lipid ratios at 3 months and subsequent growth