Gestation-specific reference intervals for renal and liver function tests and complete blood count in a Chinese cohort: a retrospective cross-sectional study

Reference intervals for renal and liver function tests and complete blood count are influenced by gestational age, ethnicity, and analytical methods. Establishing pregnancy-specific reference intervals is essential for accurate diagnosis and management of obstetric conditions. This study aimed to define gestation-stratified reference intervals for 29 biochemical and hematological parameters in a Chinese population. In this cross-sectional study, 23,514 pregnant Chinese women (aged 18–35 years) underwent prenatal check-ups across trimesters were initially enrolled. After applying exclusion criteria, laboratory data from remaining participants were retained for Reference interval establishment. Gestation-stratified RIs were established in strict accordance with CLSI EP28-A3c and WS/T 402–2024 guidelines, computing trimester-specific Reference intervals. Subsequently, decision tree modeling automated gestational age subgrouping by identifying inflection points in cross-sectional trends across gestation, enabling data-driven Reference interval construction for optimized physiological intervals. Furthermore, continuous gestational age-dependent Reference intervals were derived via the Lambda-Mu-Sigma method. Key quantitative findings included a more than two-fold increase in the upper reference limit for alkaline phosphatase by the third trimester (from 74.00 to 275.57 U/L), moderate elevations in aspartate aminotransferase, lactate dehydrogenase, and total bile acids, and progressive declines in alanine aminotransferase, albumin, and cholinesterase. Hemodilution was evident from a decline in hemoglobin (lower reference limit decreased to 98 g/L) and platelet count (lower reference limit decreased to 98 × 10⁹/L) in late pregnancy, while the white blood cell count upper reference limit rose to 14.99 × 10⁹/L. Renal function adaptations were marked by a late-pregnancy surge in uric acid (upper reference limit : 458.00 µmol/L) and cystatin C (upper reference limit: 1.54 mg/L). Pregnancy-specific reference intervals mitigate misinterpretations of hepatic, renal, and hematological parameters. Using standardized methodologies, we established trimester-stratified Reference intervals for healthy pregnancies and gestational age-specific percentile curves, enhancing evidence-based clinical precision. Conventional gestational reference intervals fail to accurately capture the dynamic physiological adaptations of pregnancy. This study is the first to establish gestation-specific reference intervals for liver and kidney function tests and complete blood count in a Chinese population. Through the novel application of decision tree modeling and the Lambda-Mu-Sigma method to generate continuous reference intervals, it provides an essential evidence base for precise obstetric diagnosis and clinical management.