Impacts of maternal lipid and homocysteine levels on the risks of pregnancy complications and adverse outcomes in both singleton and twin pregnancies: a population-based observational cohort study

BACKGROUND: In pregnancy, there is a lack of consensus on reference intervals (RIs) of serum lipids and homocysteine (Hcy) to guide clinical intervention. This population-based cohort study aimed to establish trimester-specific reference intervals of serum lipids and Hcy, and to reveal the associations between maternal lipid profiling and adverse outcomes during pregnancy. METHODS: The laboratory test results of Hcy and lipid profile, including total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C), were collected from 29,380 singleton and 840 twin pregnant women who had their regular antenatal check-ups between October 1st, 2017 and September 30th, 2019. The trimester-specific RIs of lipids and Hcy were established using both the nonparametric approach and the indirect Hoffmann method, followed by the outcome logistic association analysis. RESULTS: There was no significant difference between the observed RIs estimated with healthy pregnant women and the calculated RIs derived from the Hoffmann method (all p > 0.05). The maternal Hcy level was positively associated with the risk of preterm birth (PTB)with adjusted OR values ranged from 1.10 (95% CI 0.97-1.24) to 1.48 (95% CI 1.02-2.14) in the first trimester and from 1.63 (95% CI 1.44-1.83) to 3.46 (95% CI 2.65-4.52) in the third trimester, but negatively associated with the risk of gestational diabetes mellitus (GDM)with OR values ranged from 0.70 (95% CI 0.56-0.88) to 0.81 (95% CI 0.62-1.07). High levels of TC, TG, LDL-C and low level of HDL-C were found to be associated with increased risks in GDM, PTB, postpartum hemorrhage(PPH), intrahepatic cholestasis of pregnancy(ICP) (all OR > 1, p < 0.05). CONCLUSIONS: Our study established trimester-specific RIs of serum lipids and Hcy in both singleton and twin pregnancies, which have important clinical and research value for pregnancy health management and adverse outcome prevention.