Circulating angiogenic factors in monochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome and selective intrauterine growth restriction

OBJECTIVE: To determine maternal plasma levels of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1), placental growth factor (PLGF), and soluble endoglin (sEng) in monochorionic diamniotic (MC/DA) twin pregnancies complicated by twin-to-twin transfusion syndrome (TTTS) or selective intrauterine growth restriction (sIUGR). STUDY DESIGN: A longitudinal cohort study of pregnant women with MC/DA twins who were classified into 3 groups: (1) uncomplicated MC/DA twins (n = 22), (2) TTTS (n = 23), and (3) sIUGR (n = 15). Maternal plasma samples were obtained between 13-20 and 21-28 weeks of gestation and cord blood samples were collected at delivery. Maternal plasma concentrations of sVEGFR-1, PLGF, and sEng, as well as cord blood levels of sVEGFR-1 were measured by enzyme-linked immunoassay. RESULTS: Maternal plasma levels of sVEGFR-1 and sEng were significantly higher in patients with TTTS at the early and late second trimester compared with normal monochorionic pregnancies P < .01). In contrast, in the sIUGR group, sVEGFR-1 and sEng levels were significantly higher only at the late second trimester (P < .05). PLGF levels were significantly lower at the early and late second trimester in both TTTS and sIUGR compared with controls (P < .01). Plasma concentrations of sVEGFR-1 were significantly higher among TTTS pregnancies compared with sIUGR at the late second trimester (P = .027). Cord blood levels of sVEGFR-1 were significantly higher in the smaller intrauterine growth restricted twin compared with the normal cotwin. CONCLUSION: Monochorionic pregnancies complicated by TTTS and sIUGR are characterized by decreased angiogenic activity. The disparity in severity of the antiangiogenic state between TTTS and sIUGR suggests that these 2 conditions may represent a continuum.