Placental fatty acid transfer: a key factor in fetal growth.

The functionality of the placenta may affect neonatal adiposity and fetal levels of key nutrients such as long-chain polyunsaturated fatty acids. Fetal macrosomia and its complications may occur even in adequately controlled gestational diabetic (GDM) mothers, suggesting that maternal glycemia is not the only determinant of fetal glycemic status and wellbeing. We studied in vivo the placental transfer of fatty acids (FA) labeled with stable isotopes administered to 11 control and 9 GDM pregnant women (6 treated with insulin). Subjects received orally C-13-palmitic, C-13-oleic, and C-13-linoleic acids and C-13-docosahexaenoic acid (C-13-DHA) 12 h before an elective caesarean section. FA were quantified by gas chromatography and C-13 enrichments by gas chromatography-isotope ratio mass spectrometry. The C-13-FA concentration was higher in total lipids of maternal plasma in GDM patients versus controls, except for C-13-DHA. Moreover, C-13-DHA showed a lower placenta/maternal plasma ratio in GDM patients versus controls and a significantly lower cord/maternal plasma ratio. Other FA ratios studied were not different between GDM and controls. A disturbed C-13-DHA placental uptake occurred in GDM patients treated with diet or insulin, while the latter also had lower C-13-DHA levels in the venous cord. The tracer study pointed towards an impaired placental DHA uptake as a critical step, while the transfer of other C-13-FA was less affected. Patients with GDM treated with insulin could also have a greater fetal fat storage, which may have contributed to the reduced C-13-DHA in the venous cord observed. The DHA transfer to the fetus was reduced in GDM pregnancies compared to controls. This might have an influence on fetal neurodevelopment and long-term consequences for the child. (C) 2014 S. Karger AG, Basel