Define Placental Transfer of Nutrients?

The placenta is n transitory structure developing during pregnancy and lies implanted on the uterine wall. It is connected with the foetus through the umbilical cord. The foetus derives all its nutrition from the mother across the placental barrier.  If the consumption, absorption and utilization of the nutrients by the mother and the transport of nutrients across the placental barrier are inadequate, then foetal malnutrition develops. Dietary inadequacies are a major cause of foetal under nutrition in developing countries. Maternal diseases such as diabetes and hypertension compromise the delivery of nutrients across the placenta to the foetus.

The transfer of nutrients also depends on their concentrations in maternal plasma and blood flow to the placenta.  The mechanisms for transfer of nutrients across the placental barrier are either simple or facilitated diffusion or active transport, as in the case of transfer across the intestinal brush border. Fat-soluble vitamins and electrolytes are transferred by simple diffusion; glucose is transferred by facilitated diffusion; while amino acids, water- soluble vitamins and minerals like calcium and iron are transferred by active transport.  The role of placenta in promoting foetal nutrition is shown in the Table.