The effect of maternal smoking and ethanol on fatty acid transport by the human placenta

The role of the placenta in controlling the supply of fatty acids to the fetus was investigated in term placentas from non-smokers (n 5), smokers (>ten cigarettes/d; n 5) and after addition of ethanol at 2 mg/ml (n 4). The maternal side was of the placenta was perfused ex vivo for 90 min with a physiological mixture of fatty acids and fatty acid:human albumin ratio. There was no effect of smoking on the transfer of linoleic (LA, 18:2 n-6), alpha-linolenic (alphaLN, 18:3 n-3), arachidonic (AA, 20: 4 n-6) or docosahexaenoic acid (DHA, 22: 6 n-3), expressed per perfused area (calculated from (H2O)-O-18 exchange). However, the presence of ethanol in the perfusate at a concentration of 2 mg/ml significantly reduced (P<0.01) the absolute rate of transfer of the two n-3 polyunsaturated fatty acids, alpha LN and DHA. This specific effect of ethanol on alpha LN and DHA also resulted in an altered selectivity for transfer of individual fatty acids. In the nonsmoking control group the placenta selectively transferred polyunsaturated fatty acids to the fetus in the order DHA > AA > alphaLN > LA. The order of selectivity was unaltered in placentas from smokers, but the addition of ethanol to the perfusion medium altered the order of selectivity to AA > alphaLN > LA > DHA. The presence of ethanol in the perfusate was also associated with a significant reduction (P<0.05) in the clearance of (H2O)-O-18. These results suggest that the presence of ethanol at a concentration of 2 mg/ml may reduce the availability of polyunsaturated fatty acids to the developing fetus.