Trimester-specific reference intervals for maternal serum lipids and their associations with adverse outcomes in a...

Dyslipidemia in pregnancy is associated with increased risk of complications such as gestational diabetes mellitus, preeclampsia, and adverse perinatal outcomes. These effects might persist throughout the perinatal period and potentially affect the long-term health of both the mother and child. Presently, there is no consensus on the normal range of blood lipids during pregnancy. This study seeks to establish trimester-specific reference intervals (TSRI) for blood lipids and examine the link between dyslipidemia and adverse pregnancy outcomes (APOs).

We retrospectively analyzed clinical data from 8950 pregnant women with singleton live births at Peking University International Hospital between January 2, 2020, and May 23, 2024. Assays for total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were performed at the first, second, and third trimesters. Using strict criteria, we selected 5456 pregnant women, stratified them by pre-pregnancy body mass index (p-BMI), and established TSRI for lipid levels in each p-BMI subgroup using the percentile method. Subsequently, a logistic regression model, adjusted for confounding factors, assessed the relationship between maternal lipid profiles and APOs in the entire cohort.

Throughout all trimesters of pregnancy, HDL-C decreases as p-BMI increases; meanwhile, TG increases with higher p-BMI across all trimesters. In the first trimester, both TC and LDL-C rise with increasing p-BMI, whereas in the second and third trimesters, TC and LDL-C decrease as p-BMI increases. The TSRI, determined by the percentile method, is as follows: In the underweight group (BMI < 18.5 kg/m²): TC ranges from 2.89 to 5.37, 4.49 to 8.07, and 4.77 to 9.06 mmol/L; TG ranges from 0.40 to 1.60, 1.06 to 3.60, and 1.57 to 5.31 mmol/L; LDL-C ranges from 1.19 to 3.03, 1.96 to 4.84, and 2.12 to 5.71 mmol/L; HDL-C ranges from 1.08 to 2.25, 1.44 to 2.92, and 1.33 to 2.70 mmol/L. In the normal weight group (BMI 18.5-23.9 kg/m²): TC ranges from 2.93 to 5.38, 4.35 to 7.94, and 4.53 to 8.86 mmol/L; TG ranges from 0.41 to 1.73, 1.11 to 3.93, and 1.56 to 5.86 mmol/L; LDL-C ranges from 1.22 to 3.23, 1.84 to 4.78, and 1.88 to 5.55 mmol/L; HDL-C ranges from 1.03 to 2.03, 1.38 to 2.76, and 1.27 to 2.64 mmol/L. In the overweight and obese group (BMI ≥ 24 kg/m²): TC ranges from 2.99 to 5.71, 4.05 to 7.54, and 4.17 to 8.18 mmol/L; TG ranges from 0.44 to 2.17, 1.31 to 4.46, and 1.74 to 6.26 mmol/L; LDL-C ranges from 1.33 to 3.63, 1.64 to 4.52, and 1.69 to 5.00 mmol/L; HDL-C ranges from 0.90 to 1.94, 1.22 to 2.54, and 1.17 to 2.57 mmol/L. Elevated levels of TC, TG, and LDL-C, or decreased HDL-C during pregnancy, correlate with an increased risk of APOs. Among the lipids measured, TG had the strongest link to APOs. This negative relationship was evident across all trimesters and became more pronounced as TG levels increased during pregnancy. Further, blood lipids exhibit a bidirectional influence on fetal weight.

The use of TSRI is recommended for the identification of dyslipidemia during pregnancy. Deviations of lipid levels from TSRI are significantly associated with the occurrence of APOs.