General obesity index or central obesity indicators: which is a better predictor of body fat percentage in the first trimester?

OBJECTIVE: To compare general and central obesity indicators in their association with body fat percentage (BFP) in early pregnancy. METHODS: A retrospective study was carried out involving 10,267 women with singleton pregnancy who completed their first prenatal examination and body composition assessment at a tertiary women and children's hospital between January 2020 and December 2021. Data extracted from the hospital information system included personal information, BFP, the general obesity indicator (BMI), and central obesity indicators such as waist circumference (WC), hip circumference (HC), waist-hip ratio (WHR), and waist-height ratio (WHTR). The associations between BFP and obesity indices were calculated by Pearson correlation. The predictive performance of the general obesity index and central obesity indicators for estimating BFP was evaluated by the receiver operating characteristic (ROC) curve and its area under the curve (AUC). RESULTS: WHTR, WC, BMI, HC, and WHR were significantly correlated with BFP (p < 0.001 for all) in early pregnancy. The AUC values of WHTR, WC, BMI, HC, and WHR for predicting BFP were 0.89, 0.86, 0.85, 0.82, and 0.81, respectively. The combined effects of BMI, WC, HC, WHR, and WHTR on BFP were the largest (AUC = 0.92). CONCLUSIONS: All anthropometric obesity indices in early pregnancy were related to BFP. The most accurate and cost-effective approach for estimating BFP in early pregnancy was the combined use of WHTR, WC, BMI, HC, and WHR. With limited time and measurement conditions, WHTR may be the optimal obesity indicator to estimate BFP, followed by WC and BMI.