Early Pregnancy Waist Circumference for Prediction of Fetal Macrosomia.

Fetal macrosomia is associated with adverse short- and long-term outcomes for the mother and the child. Present models to predict fetal macrosomia cannot be used in all settings, and their precision could be improved. We assessed if waist circumference could replace or outperform weight for early pregnancy prediction of macrosomia. We included 5827 women in this population-based cohort study and assessed the influence of early pregnancy waist circumference and weight on the prediction of macrosomia with logistic regression analysis. We generated receiver operating characteristic (ROC) curves and calculated the area under the curve (AUC) to compare models, including waist circumference, weight, or neither of them. The odds of macrosomia increased with a larger waist circumference (adjusted odds ratio (AOR) 1.03 (95% Confidence Interval (CI) 1.02, 1.04)). For women with waist circumference between 80 and 88 cm the AOR was 1.41 (95% CI 1.09, 1.82) and women with waist circumference ≥ 88 cm had AOR 1.98 (95% CI 1.56, 2.53) for macrosomia. There was no difference in predictive capacity between waist circumference and weight in the macrosomia prediction model. The AUC was 0.75 (95% CI 0.72, 0.77) for waist circumference and 0.74 (95% CI 0.72, 0.77) for weight. The model that excluded waist circumference and weight had an AUC of 0.72 (95% CI 0.70, 0.75). The predictive capacity of the model including waist circumference was, however, higher than that of the model without waist circumference or weight (p < 0.001). In conclusion, waist circumference can replace weight in an early pregnancy macrosomia prediction model.