Reproduction is the fundamental process to sustain life. A healthy pregnancy is dependent on two biological processes: maternal immune tolerance towards the fetus and angiogenesis, the formation of new blood vessels, in the placenta to supply the fetus with nutrients and oxygen. Both processes require galectin-1. Galectin-1 belongs to the protein family of carbohydrate-binding lectins. The circulating and local levels in the female reproductive tract increase during pregnancy. This book shows that the lack of galectin-1 results in a compromised angiogenic development leading to preeclampsia-like symptoms in mice. In pregnant women with preeclampsia, galectin-1 is also dysregulated. Preeclampsia is a multisystemic disorder characterized by hypertension and proteinuria and for which no cure is available. The clinical symptoms appear in the second half of pregnancy and only resolve after delivery. In severe cases a premature birth is necessary. Both the mother and the fetus carry a higher risk for the development of cardiovascular diseases during later life. This book describes the possible use of galectin-1 as a biomarker for the early detection of high-risk preeclampsia patients.