Maternal consumption of trans-fatty acids during the first half of gestation are metabolically available to suckled newborn rats.

Dietary trans-fatty acids (t-FA) during pregnancy have adverse effects on growth and development. To determine the effect of dietary t-FA during just the first half of pregnancy, rats were given a diet containing 8 % hydrogenated peanut oil and 2 % olive oil (PO) and compared to rats given a diet containing 10 % olive oil (OO). After 12 days all rats were fed standard diet and were studied at days 12 or 20 of pregnancy or days 1 or 6 postpartum. At day 12 of pregnancy there were small differences in the plasma and lumbar adipose tissue fatty acid profiles and elaidic acid [18:1(n-9)t] was present in the PO group. From day 12 to 20 of pregnancy, plasma non-esterified fatty acids, glycerol, triacylglycerols (TAG) and most individual fatty acids increased more in PO than in OO. At day 20 of pregnancy in the PO group most plasma elaidic acid appeared as plasma TAG and was also present in the mammary gland, to decline in both sites at day 1 postpartum. Elaidic acid concentration was low in the plasma of 20-day fetuses, increased in 1-day newborns declining at day 6. Thus t-FA, eaten during early pregnancy, accumulated in maternal adipose tissue and were released during late pregnancy to be taken up by the mammary gland becoming available to the newborns during suckling.