Gestational age-specific reference intervals for placental growth factor and its application in singleton and twin pregnancies: a population-based cohort study

> 0.05). Using the 2.5th-97.5th percentile ranges, gestational age-specific RIs were defined for both cohorts. In validation cohorts comprising pregnancies complicated by preeclampsia (PE), fetal growth restriction (FGR), placental abruption (PA), or postpartum hemorrhage (PPH), PLGF thresholds were stratified relative to lower reference limits (LRLs). PLGF concentrations below 80%, 100%, and 120% of LRLs were strongly associated with elevated risks for all studied complications. Adjusted logistic regression models demonstrated a dose-dependent relationship, with adjusted odds ratios (aOR) escalating inversely to PLGF thresholds: aOR = 3.2 (95% CI: 2.5-4.1) at 120% LRL, increasing to aOR = 8.7 (95% CI: 6.3-12.0) at 80% LRL. These findings confirm that trimester-specific PLGF RIs effectively stratify pregnancy risks, with sub-LRL values serving as independent predictors of adverse outcomes. This established RIs enhance obstetric risk assessment frameworks, supporting PLGF integration as a complementary biomarker for targeted monitoring and early intervention in both singleton and twin pregnancies.