Successful pregnancy outcome depends on a co-coordinated series of events in development designed to attain normal placental function. The critical importance of placental vascular development is appreciated when a wide range of pregnancy complications including preterm labour (PTL), preterm premature rupture of the membranes (PPROM), pre-eclampsia (PE), fetal growth restriction (FGR), fetal demise (FD), and abruptio placenta (ABR) are all associated with restricted maternal and/or fetal blood flow, and secondary pathological lesions in the placental parenchyma. Other developmental defects of the placenta, such as its site (placenta praevia), extent of myometrial invasion (placenta accreta) or cord insertion (vasa praevia), may have major detrimental maternal and/or fetal effects if unrecognized during the antenatal period. In January 1999 we commenced a â€œPlacenta Clinicâ€� within the Fetal Medicine Unit at Mount Sinai Hospital (Toronto, Canada). Our rationale was that the early identification of many of these problems may, by facilitating appropriate multidisciplinary care and an elective delivery plan, reduce the attendant risks of maternal and perinatal morbidity and/or mortality due to placental malfunction.