Pregnancy is a critical time of altered metabolic function and changed lipid profiles. Maternal hyperlipidemia has been shown to be associated with maternal and offspring adverse outcomes, yet no consistence reference values for lipids exist in pregnancy period, and there are no recommended lipid levels for Chinese pregnant women. The object of this study was to describe lipid levels during pregnancy and establish the reference ranges of lipids in Chinese pregnant women.

In total, 14,739 pregnant females and 183,787 non-pregnant females who underwent measurement of serum lipids were taken as parent dataset. For controlling confounding from age and BMI, a 1:1 matched pair analysis was used to compare the difference in lipid levels between pregnant and non-pregnant females. Pairs were matched by BMI (± 1kg/m²) and age (±1 year). Multi-index method was used to determine reference ranges in healthy pregnant women with normal pre-pregnancy BMI.

Concentrations of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were higher in pregnant women compared to non-pregnant women. With pregnancy development, TC, TG, and HDL-C increased from 1st trimester to 2nd and 3rd trimesters, and LDL-C decreased in the third trimester. The reference ranges were recommended as the levels of TC no greater than 9.02mmol/L, TG no greater than 5.88mmol/L; HDL-C no less than 1.03mmol/L and LDL-C no greater than 5.65mmol/L.

Obvious higher lipid concentrations were observed during pregnancy compared to non-pregnant females. Hence, reference ranges of lipid profiles from the general population are not appropriate for pregnant women. Furthermore, this study provided reference ranges of lipid profiles for Chinese pregnant women.