Background: Placental insufficiency is a major contributor to maternal and neonatal morbidity and mortality. People with type 1 (T1DM) or type 2 diabetes (T2DM) have a 2–4-fold increased risk of placental dysfunction, often presenting as preeclampsia (PE) or fetal growth restriction (FGR). Diagnosing placental insufficiency is challenging due to comorbidities such as hypertension and nephropathy, and as FGR may occur in a seemingly appropriately grown fetus. This study investigates the utility of routine screening using sFlt-1/PlGF >38 or PlGF <100pg/ml to detect placental insufficiency in pregnancies complicated by T1DM or T2DM.
Methods: A prospective observational cohort study; 98 pregnant individuals (58 with T2DM, 40 with T1DM) were recruited. Blood samples for sFlt-1 and PlGF were collected at 20, 24, 28, 32, and 36 weeks gestation. Clinicians were blinded to results unless ordered outside protocol. Samples were frozen and analysed post-delivery. Outcomes included the incidence of clinical placental insufficiency and abnormal biomarker values at each time point.
Results: Aspirin prophylaxis was high (94.8% T2DM, 97.5% T1DM). Clinical placental insufficiency (PE, FGR) was identified antenatally in 31 (31.6%) vs abnormal placental biomarkers in 45 (45.9%); 13 (31.6%) vs 21 (52.5%) in T1DM, 18 (31.0%) vs 24 (41.4%) in T2DM respectively. Abnormal biomarkers were associated with preterm birth and fetal distress leading to emergency CS. Useful testing periods were 24-28 weeks gestation with a PlGF, and at 35-36 weeks with sFlt-1/PlGF.
Conclusion: Biomarker testing revealed that 31% of clinically important placental insufficiency was missed in this cohort by current standard screening measures.