Lipid Metabolism in Pregnancy. III. Altered Lipid Composition in Intermediate, Very Low, Low, and High-Density Lipoprotein Fractions

Abstract

The hyperlipidemia of pregnancy consists primarily of an increase in triglyceride with lesser rises in cholesterol and phospholipid. As a further characterization, we have analyzed all lipids in the major lipoprotein subfractions in fasting pregnant and non-pregnant women. An elevated triglyceride in the major lipoprotein fractions in pregnancy is confirmed. The triglyceride rises in VLDL and IDL (density 1.006-1.019 lipoprotein) are associated with proportional rises in cholesterol and phospholipid. The result is a 3-4-fold increase of compositionally unchanged lipoprotein lipid. Contrasting changes are seen in LDL, density 1.019-1.063 lipoprotein, and HDL. In these fractions, triglyceride rises more than cholesterol and phospholipid. As a result, an increase in triglyceride on a percentage basis tends to reduce the contribution of the other two lipids. Nonetheless, on an absolute basis HDL cholesterol is not significantly reduced. The proportional increases in all lipids of VLDL and IDL fractions are consistent with increased VLDL production in pregnancy as suggested by data from animal systems. However, alterations in removal are not rules out. Maintenance of the HDL cholesterol level distinguishes pregnancy from other endogenous hypertriglyceridemias where HDL cholesterol is reduced. One may speculate that these physiological adaptations in material lipid transport can serve the increased energy needs of the mother, supply steroid hormone precursors for the placenta, and provide cholesterol and essential fatty acids for the fetus.

Hypertriglyceridemia: its etiology, effects and treatment

“…During the third trimester of pregnancy, plasma triglyceride levels normally rise to as much as threefold, 11 but this physiologic triglyceride increase has little clinical consequence. Marked triglyceride increases also result, however, when lipoprotein lipase activity is compromised.…”

Sex Steroid Modulation of Fatty Acid Utilization and Fatty Acid Binding Protein Concentration in Rat Liver

“…These clinical effects include increased plasma triglyceridle levels associated with pharmacological estrogen treatment, oral contraceptive administration, and pregnancy (42)(43)(44), and the decreased levels produced by androgenis and progestational agents including norethindrone (45) and oxandrolone (46). Additional studies in this important area may be expected to further clarify the determinants of hepatic fatty acid uptake and utilization, and may have therapeutic implicatioins as well.…”

Modulation of placental protein expression of OLR1: implication in pregnancy-related disorders or pathologies

“…Physiological adaptations of maternal lipoprotein metabolism occur throughout pregnancy, leading to an increase in lipoprotein concentrations from second trimester to term. Maternal hypercholesterolemia is a characteristic feature during pregnancy and corresponds to an accumulation of triglycerides (TGs) in very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL; Warth et al 1975, Herrera 2002. Although the exact mechanism of cholesterol transport across the placenta remains unclear, many studies suggest the implication of HDL as well as LDL, both providing cholesterol for placental hormone synthesis (Gwynne & Mahaffee 1989).…”