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.