A proposed fetal risk scoring system for gestational diabetes to assist in optimising timing of delivery

Abstract

Background. The pathophysiology of gestational diabetes, which is related to abnormal gluocose tolerance and hyperinsulinaemia, renders standard fetal monitoring models ineffective, insufficient and inappropriate, as these models revolve around detecting and prognosticating on placenta-mediated disease rather than increased metabolic rates due to hyperinsulinaemia, functional hypoxia and ischaemic trophoblastic thresholds. To improve perinatal morbidity and mortality in gestational diabetes, there is therefore a need to introduce new prognostic parameters and scoring systems. Objectives. A proposed risk scoring system has been developed, based on our previous studies, to risk-categorise patients with gestational diabetes in terms of fetal outcome in view of the fact that the pathophysiology of gestational diabetes is not recognised by standard monitoring models, which revolve around placental insufficiency rather than metabolic anomalies.Methods. Patients with diabetes from four case-control studies were combined to form a total sample of 159 cases for validation of the risk scoring system. Univariate logistic regression analysis was used to assess the effect of individual risk factors with proposed cut-offs on adverse pregnancy outcome. The diagnostic accuracy of the total summative score was assessed by computing the area under the receiver operating characteristic (ROC) curve. Results. Four potential parameters were identified to risk-categorise fetuses in a pregnancy complicated by gestational diabetes, i.e. the myocardial performance index (MPI), the E/A ratio (early diastolic filling/late diastolic filling, a marker of diastolic dysfunction), increasing fetal weight (macrosomia), and an increased amniotic fluid index. The total score, obtained by summation of the composite scores for these parameters, ranged from 0 to 11. The total score performed as an excellent predictor of adverse outcome, evidenced by an ROC area under the curve of 0.94. A cut-point of 6 on the score confers a sensitivity of 84.2% and specificity of 90.2% for predicting adverse outcome. Conclusion. To our knowledge, this is the first gestational diabetes scoring system proposed to predict an adverse outcome.