Is normal pregnancy atherogenic?

Serum cholesterol, triacylglycerols and low-density lipoprotein (LDL) subfractions were determined in 120 primagravid women during normal gestation (40 in each trimester) and in 20 non-pregnant age-matched controls. LDL subfractions were determined by PAGE, and an LDL score was calculated. The higher the score, the smaller the subfractions. The objective of the study was to determine the effects of the hyperlipidaemia, high oestrogen concentrations and insulin resistance known to exist in normal pregnancy on LDL subfraction formation. Pregnant women had an increased mean serum cholesterol concentration [5.78 (S.D. 1.09) mmol/l] in the first trimester compared with the non-pregnant controls [5.11 (0.77) mmol/l; P<0.01]. The serum cholesterol concentration increased progressively throughout gestation to a mean of 8.14 (1.39) mmol/l in the third trimester (P<0.001 compared with the second trimester). Triacylglycerol concentrations in the first trimester were similar to those of controls, and there was a non-significant increase by the second trimester to 1.32 (0.44) mmol/l. However, by the third trimester the mean triacylglycerol concentration had doubled [2.58 (0.98) mmol/l; P<0.001 compared with the first and second trimester]. During gestation the LDL score increased dramatically, from 1.17 (0.39) during the first trimester to 2.01 (0.37) in the second trimester (P<0.001) to 2.73 (0.48) in the third trimester (P<0.001 compared with the second trimester). Thus an atherogenic lipid profile develops during normal gestation. The significance of these changes remains unclear, but thay may have important implications for mother and foetus.