Abstract
Three different series of healthy pregnant women without any history or symptoms of metabolic disorder have been studied for serum lipids (cholesterol), triglycerides and phospholipids) as well as for cholesterol and triglyceride content in lipoprotein fractions in the 1st, 2nd and 3rd trimesters. Two other series of non-pregnant healthy women, previously studied for serum lipids, are presented for comparison. In the 1st trimester, serum cholesterol decreased (p<0·01) as compared to non-pregnant values. In the 2nd and 3rd trimester all serum lipids increased successively with maximum values during 3rd trimester all serum lipids increased successively with maximum values during 3rd trimester. The changes were most pronounced in serum triglycerides. Among lipoproteins, cholesterol content increased in all fractions during the 2nd trimester and was most pronounced in very-low-density lipoproteins (VLDL) (in the 2nd trimester by 78 per cent and in the 3rd trimester by an additional 94 per cent). The increase in triglycerides in the 1st and 2nd trimester was most pronounced in infranatant (LDL + HDL), while in the 3rd trimester the triglyceride content was more evenly distributed among infranatant and supernatant (VLDL) at density 1 006 g/ml. It is suggested that the increase in triglycerides is due to increased liver synthesis in the 1st and 2nd trimester concomitant with an enhanced removal, i.e. by increased lipoprotein lipase activity (LPLA). In the 3rd trimester, however, LPLA is possibly inhibated by subclinical cholestatic changes in the liver causing a maximum triglyceride accumulation preferentially located in VLDL. In an earlier study dealing with serum lipid changes in diabetic pregnancy, marked hyperlipidemia in ihe 3rd trimester was a characteristic feature (23). Furthermore, elevated serum triglycerides in the mother appeared to be related to an increased birth weight of her infant. A long parallel study was needed in normal pregnancy to allow a comparison with the serlim lipid variables in diabetes. The aim of the present investigation was to study serum lipids and lipoprotein, distribution in normal pregnancy.