Myometrial PTGS expression is prematurely elevated in IUGR-associated pregnancies in the guinea pig and IUGR pregnancies are associated with significant down regulation of HPGD expression in the visceral yolk sac membrane (Figure 1), which assumes the role of the chorion laeve in many other mammals (Figure 3), (Kaufmann and Davidoff, 1977; Palliser et al., 2014). Here, HPGD is linked to fetal growth restriction.