ENG and preeclampsia: Studies have shown that maternal circulating levels of placenta-derived anti-angiogenic proteins such as circulating endoglin (ENG) and soluble fms-like tyrosine kinase 1 receptor (sFLT1) are significantly higher in pregnancies complicated by preeclampsia than in normotensive control and pure intrauterine growth restricted (IUGR) pregnancies3–5.