Multiple pregnancies are thought to be associated with a high incidence of perinatal complications such as preterm labor, preeclampsia and low birth weight. But the true mechanisms of these obstetric complications are still uncertain. The components of amniotic fluid reflect the pathophysiology features of the fetus. Amniotic fluid soluble fms-like tyrosine kinase 1(sFLT1), soluble endoglin (sENG), and adiponectin reflect the oxidative stress and pro-inflammatory status and are associated with preeclampsia and fetal growth restriction. We prospectively collected amniotic fluids during amniocentesis from singleton and twin pregnancies. Samples were analyzed for levels of sFLT1, sENG, and adiponectin by enzyme-linked immunosorbent assay. The levels of sENG and sFLT1 were significantly increased in twin pregnancies. Adiponectin was not significantly different between the two groups. These findings would suggest that twin fetuses suffer from more oxidative stress and pro-inflammatory status from the early trimesters.