During pregnancy, the fetus receives from its mother a continuous intravenous supply of energy substrates via the placenta. In most species, plasma lipids do not readily cross the placenta. In the human, where the placental transfer oflipids is limited, these substrates do not contribute to fetal oxidative metabolism since fetal tissues have a very low capacity for free fatty acids (FFA) oxidation. The FFA that cross the placenta are stored in adipose tissue and liver. 'When the mother is well fed, the supply of glucose and amino acids to the fetus is sufficient to cover its needs for oxidative metabolism and growth, and the fetus has no need to produce endogenous glucose. Excess of glucose is stored as glycogen in many tissues, particularly in the liver and as lipids in adipose tissue. After birth, the continuous intravenous high-carbohydrate low-fat diet ofthe fetus is replaced by a discontinuous enteral high-fat lowcarbohydrate diet.

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Friesland Nutrition, Abbott B.V., Driiger Medical, Glaxo Wellcomc B.V., Lifcscan, Mead Johnson Nutritionals, Nutricia Nederland B.V.
P.J.J. Sauer (Pieter)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

van Beek, R. (2001, October 24). Metabolism in preterm infants on the first days of life: The effect of corticosteroids. Retrieved from http://hdl.handle.net/1765/23543