Progressive decrease in plasma ω3 and ω6 fatty acids during pregnancy: Time course and effects of dietary fats and antioxidant nutrients

As part of a previously reported comprehensive study of the nutritional and environmental factors contributing to oxidative stress during pregnancy, breath ethane, a volatile alkane produced during peroxidation of ω3 fatty acids (FAs), was used as a non-invasive measure of oxidative stress. This study investigates relationships between the plasma concentration of ω3 FAs, breath ethane, nutrient intake and serum concentration of selected antioxidant nutrients. The study design included measurement of breath ethane, the plasma phospholipid fatty acid (PLFA) profile, serum vitamins A, C, E, carotene, selenium, zinc, copper and manganese and dietary intake of 44 women studied at the 28-week gestation (2T) routine outpatient visit. Plasma lipids were extracted, phospholipids (PL) were isolated, and the FA compositions were measured by capillary gas chromatography. None of the plasma ω3 FAs correlated with breath ethane, serum concentration or dietary intake of antioxidants. Since the PLFA profile of the 2T group revealed decreased plasma ω6 and ω3 FAs compared to healthy (previously reported) non-pregnant females (NPF) of child-bearing age, a cross-sectional study was done to compare the PLFA profile of the 2T group to that of women in the first (1T) and third (3T) trimester of pregnancy to determine if there were deficiencies that progressed during pregnancy. The 1T group (n = 16) was studied at 11-14 weeks gestation; the 2T group as above; and the 3T group (n = 19, previously reported), at 34-39 weeks as well as during labor. In comparison to values for NPF (n = 59), there was a progressive decrease during pregnancy of most ω3 and ω6 essential FAs. The sum of ω6 FAs (expressed as % of total FA in PL of plasma) decreased from 41.75 ± 0.29% for NPF to 38.36 ± 0.50% (1T), 36.80 ± 0.32% (2T) and 34.55 ± 0.41% (3T). The sum of ω3 FAs was 5.50 ± 0.16% for NPF, 5.80 ± 00.2% (1T), 4.99 ± 0.12% (2T) and 3.16 ± 0.19% (3T). The results of this cross-sectional study suggest a progressive transfer of ω6 and ω3 fatty acids from mother to fetus during pregnancy, as lipid peroxidation and dietary deficiency seem less likely explanations for these deficiencies.