Reference intervals of serum lipids in the second and third trimesters of pregnancy in a Caucasian cohort: the LIFE Child study

Background The study aimed to establish reference intervals for serum lipids and apolipoproteins in pregnant women depending on trimester and parity, and to investigate the influence of various factors on lipid and apolipoprotein concentrations. Materials and methods A total of 748 pregnant women (n = 683 in the second trimester, n = 676 in the third trimester) were included in the study and reference intervals for total cholesterol (TC), HDL, LDL, triglycerides (TG), apoA1 and apoB were determined as empirical quantiles. The measurement of serum lipids was performed using a validated specific homozygous enzymatic color test. Hierarchical models were used to investigate hypothesized relations. Results Except for apoA1, all serum lipids levels showed a significant change from the second to the third trimester. This increase was most pronounced for TGs. Especially in the third trimester, the concentrations of serum lipids exceeded the currently accepted reference values for non-pregnant women by a factor of 2.5. Reference intervals of serum lipids at the second and third trimesters in healthy pregnant women were as following: TC 4.45-8.99 and 4.83-9.71 mmol/l, HDL 1.33-3.06 and 1.16-3.13 mmol/l, LDL 2.14-6.11 and 2.35-6.98 mmol/l, TG 0.92-3.0 and 1.37-4.76 mmol/l as well as apoB 0.69-1.93 and 0.85-2.21 g/l. Parity and nutrient intake were not significantly associated with changes in lipid concentration. Prematurity was associated with a significant decrease in TC and TG levels. Conclusion Detailed reference values for serum lipids and apolipoproteins in pregnancy are now available for a Caucasian cohort. Further, long-term studies are still needed to assess the effect of the extensive concentration changes of serum lipids in pregnancy and their atherogenic risk definitively.