Anomalies of the placenta and umbilical cord in twin gestations

Prenatal diagnosis and management of vasa previa in twin pregnancies: a case series and systematic review

“…[1][2][3][4][5][6][7][8] VCI and VP type I are also more common in twin pregnancies and monochorionicity doubles the risk for VCI compared to dichorinicity. 11,12 Maternal smoking has been recently reported as a risk factor for VCI and thus potentially of VP. 13 Assisted reproduction technology (ART) and in vitro fertilization (IVF) in particular is associated with a higher incidence of abnormally shaped placenta, placenta previa and cord insertion outside the placental chorionic plate.…”

“…4,6-8, 29,38 The incidence of succenturiate lobes and other morphological placental anomalies is higher in twin pregnancies. 1,11,39,40 A VCI of one of the umbilical cords is eight times more common in twins than in singletons. 39 The odd ratio for VP in pregnancies presenting with a bilobated placenta or with succenturiate lobe has been evaluated to be 22.11 in twin pregnancies.…”

Placental weight and birth weight to placental weight ratio in monochorionic and dichorionic growth-restricted and non-growth-restricted twins

“…In contrast to their results, we did not observe an increased BW/PW ratio, which may be due to the combined placental weight and the possible influence of the co-twin’s placental weight. Nevertheless, the increased BW/PW ratio in their study was due to the very low placental weight of the IUGR twin, which supports the assumption that these cases of early, severe IUGR originate from unequal placental sharing 12,13. Few studies have investigated placental weight and the BW/PW ratio in MC IUGR twins, which limits further conclusions.…”

“…In spite of the association between peripheral cord insertion and IUGR MC, there was no relation between cord insertion type and placental weight or BW/PW ratio (Table 4). This finding suggests that the influence of peripheral cord insertion on birth weight is more related to unequal vascularization 12,13 in these twins rather than placenta size.…”

“…At 35 weeks and older, no difference between IUGR and nIUGR in MC twins was observed in placental weight, but there was a significantly lower BW/PW ratio; this is perhaps because the placenta in these IUGR cases is bigger with greater functionality, and these are probably less severe cases in which the pregnancy can be maintained until a later gestational age. Furthermore, MC twins with IUGR that require early delivery have a very small placenta resulting from unequal placenta sharing and unbalanced vascular anastomoses 12,13, with consequent severe growth restriction; conversely, the cases with later delivery have an equally shared placenta, and the growth restriction may be more related to unbalanced inter-twin transfusion mediated by vascular anastomoses in the placenta rather than placenta size 12,13.…”