Role of cerebroplacental ratio in predicting the outcome of pregnancies complicated by diabetes

Introduction: Our objective was to evaluate the strength of association and diagnostic performance of cerebroplacental ratio (CPR) in predicting the outcome of pregnancies with pre- and gestational diabetes mellitus. Methods: Pubmed, Embase, Cochrane and Google Scholar databases were searched. Inclusion criteria were pregnancies with gestational or pre-gestational diabetes undergoing assessment of CPR. The primary outcome was a composite score of perinatal mortality and morbidity as defined by the original publication. Secondary outcomes included preterm birth (PTB), gestational age (GA) at birth, mode of delivery, birthweight, perinatal death (PND), Apgar score < 7 at 5 minutes, abnormal acid-base status, neonatal hypoglycemia, admission to neonatal intensive care unit (NICU) Head-to-head meta-analyses were used to directly compare the risk of each of the explored outcomes. For those outcomes found to be significant, computation of diagnostic performance of CPR was assessed using bivariate model. Results: Six studies (2743 pregnancies) were included. The association between low CPR and adverse composite perinatal outcome was not statistically significant(p= 0.096. In pregnancies complicated by GDM, fetuses with a low CPR had a significantly higher risk of birthweight <10th percentile (OR: 5.83, 95% CI 1.98-17.12) and this association remains significant when using a CPR <10th centile (p<0.001). Fetuses with low CPR had also a significantly higher risk of perinatal death (PND) (OR: 6.15 p<0.001) and admission to neonatal intensive care unit (NICU) (OR 3.32 , p<0.001), but not of respiratory distress syndrome (RDS) (p= 0.752), Apgar score <7 at 5 minutes (p=0.920), abnormal acid base status (p= 0.522) or neonatal hypoglycemia (p= 0.005). However, CPR showed a low diagnostic accuracy for detecting perinatal outcomes. Conclusion: CPR is associated but not predictive of adverse perinatal outcome in pregnancies complicated by gestational diabetes. The findings from this systematic review do not support the use of CPR as a universal screening for pregnancy complication in women with diabetes.