Screening and Prognostic Performance of Pre-Pregnancy BMI for Predicting Gestational Diabetes Mellitus in Asian...

Background: The appropriateness of the World Health Organization (WHO) body mass index (BMI) cut-off (≥25 kg/m²) for gestational diabetes mellitus (GDM) screening in Asian populations remains controversial due to the "Asian phenotype," characterized by higher body fat percentage and visceral adiposity at lower BMI values. This systematic review evaluated the screening and prognostic performance of pre-pregnancy BMI thresholds (≥23, ≥24, ≥25 kg/m²) for predicting GDM in Asian women. Methods: A systematic review and meta-analysis were conducted following the JBI Manual for Evidence Synthesis and PRISMA-DTA guidelines. A comprehensive search was performed in PubMed, Scopus, Embase, CINAHL, Cochrane Library, and Google Scholar from January 2015 to August 2024. Studies reporting screening and prognostic performance of pre-pregnancy BMI for GDM prediction in Asian populations were assessed using the QUADAS-2 tool. Data were synthesized using MetaBayesDTA for univariate random-effects meta-analysis of sensitivity and specificity. A supplementary DerSimonian-Laird random-effects meta-analysis of odds ratios (ORs) was conducted to assess the prognostic association between BMI thresholds and GDM risk. Results: A total of 13 studies were included in the review, comprising a total of 427,159 Asian pregnant women. Most included studies were conducted in East Asian populations, predominantly Chinese, and findings may not generalize to South or Southeast Asian subgroups. For the Asian-standard threshold (≥23 kg/m²; n = 3 studies), pooled sensitivity was 0.47 (95% CrI 0.45-0.49) and specificity was 0.71 (95% CrI 0.56-0.83). For the intermediate threshold (≥24 kg/m²; n = 7 studies), sensitivity was 0.31 (95% CrI 0.25-0.37) and specificity 0.84 (95% CrI 0.80-0.88). For the WHO standard (≥25 kg/m²; n = 3 studies), sensitivity was 0.31 (95% CrI 0.11-0.61) and specificity 0.80 (95% CrI 0.45-0.95). Heterogeneity was extremely high for BMI ≥ 25 kg/m² (I² = 92% for sensitivity), substantially limiting the interpretability of pooled estimates for this threshold. Conclusions: Based on low-certainty evidence from three studies with very high heterogeneity, the WHO BMI criterion (≥25 kg/m²) appears to have clinically insufficient sensitivity for GDM detection in East Asian populations. The Asian-standard threshold (≥23 kg/m²) shows improved prediction (moderate-certainty evidence) but still misses approximately 53% of true positives. Supplementary OR meta-analysis confirms that all three thresholds are significantly associated with GDM risk (pooled ORs 1.80-2.38), though effect sizes are modest. BMI alone is insufficient for GDM screening and should be integrated into multifactorial risk assessment strategies. These findings apply primarily to East Asian populations and may not generalize to South or Southeast Asian subgroups.