Is normal pregnancy atherogenic?

Serum cholesterol, triacylglycerols and low-density lipoprotein (LDL) subfr actions were determined in 120 primagravid women during normal gestation (4 0 in each trimester) and in 20 non-pregnant age-matched controls. LDL subfr actions were determined by PAGE, and an LDL score was calculated. The highe r the score, the smaller the subfractions. The objective of the study was t o determine the effects of the hyperlipidaemia, high oestrogen concentratio ns and insulin resistance known to exist in normal pregnancy on LDL subfrac tion formation. Pregnant women had an increased mean serum cholesterol conc entration [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 cholestero l 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 secon d trimester). Triacylglycerol concentrations in the first trimester were si milar 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 th e mean triacylglycerol concentration had doubled [2.58 (0.98) mmol/l; P < 0 .001 compared with the first and second trimester]. During gestation the LD L 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 t hird trimester (P < 0.001 compared with the second trimester). Thus an athe rogenic lipid profile develops during normal gestation. The significance of these changes remains unclear, but thay may have important implications fo r mother and foetus.