Angiogenic growth factors are critical to the development of both maternal and fetal vasculature at the uteroplacental interface. Our **data** suggest that T3 affects the timely decidual secretion of three key angiogenic growth factors implicated in human placentation. In the first trimester, VEGF-A, which promotes maternal and fetoplacental angiogenesis (Wulff et al., 2003) as well as EVT motility (Lash et al., 1999), is downregulated by T3 in total decidual cells. This is appropriate as it is at a time prior to the peak of EVT invasion when invasion needs to be tightly controlled. In contrast, Ang-2, which destabilizes vasculature and mediates some of the initial stages of spiral artery remodelling , is appropriately up-regulated in stromal-depleted cells in preparation for the next phase of placentation. In the second trimester, the secretion of angiogenin (a potent inducer of angiogenesis whose placental expression increases with gestation (Rajashekhar et al., 2002)) by total decidual cells is suitably up-regulated by T3.