KDR and twin to twin transfusion syndrome: With an important role of VEFGR-1 and VEGFR-2 in blood vessel formation and fetal development and of interleukins in the pathogenesis of TTTS, we investigate the concentrations of soluble VEFGR-1, VEGFR-2, IL-1β, IL-6, and IL-8 in women with and without TTTS during pregnancy and TTTS patients before and after surgical treatment.