Low density lipoprotein particle size decreases during normal pregnancy in association with triglyceride increases

OBJECTIVE: To characterize the changes in low-density lipoprotein (LDL) peak particle diameter (diameter of the predominant LDL subclass) in relation to changes in serum triglyceride concentration during successive stages of normal gestation and postpartum. METHODS: Nonfasting venous blood was obtained longitudinally during and after uncomplicated primiparous pregnancy from 10 nonsmoking women with no history of metabolic disorders. Plasma LDL diameter was determined by nondenaturing polyacrylamide gel electrophoresis. Serum concentrations of total cholesterol, triglyceride, apolipoprotein B, apolipoprotein A-I, and LDL-cholesterol were measured. Gestational changes were analyzed by one-way repeated-measures analysis of variance and the paired multiple comparison Student-Newman-Keuls test. Pearson coefficients were computed for correlation of serum lipids and LDL diameter. Results: Low-density lipoprotein diameter decreased progressively with advancing gestation, evident by 16-20 weeks relative to 5-12 weeks. Seven of 10 cases were subclass pattern B (diameter less than 255 Angstrom or more) by 6-12 weeks with concentrations of serum triglyceride (r = -.61, P < .0001), apo B (r = -.66, P < .0001), cholesterol (r = - .53, P < .001), LDL cholesterol (r = -.45, P < .005), and apo A-I (r = -.39, P < .02). CONCLUSION: Gestational triglyceride increases are accompanied by progressive decreases in LDL diameter in a majority of cases. These changes undergo reversal postpartum and therefore are transient. Small, dense LDL particles have a number of properties capable of altering vascular function. However, the consequences of the gestational LDL size decrease for maternal and fetal metabolism remain unknown. Copyright (C) 1998 by the Society for Gynecologic Investigation.