Placental vascularity and markers of angiogenesis in relation to prenatal growth status in overnourished adolescent ewes

Abstract Introduction Placental vascularity may be important in the development of fetal growth restriction (FGR). The overnourished adolescent ewe is a robust model of FGR, with ∼50% of offspring demonstrating FGR (birthweight >2 standard deviations below optimally-fed control mean). We studied if placental vascularity, angiogenesis and glucose transport reflected FGR severity. Methods Singleton pregnancies were established in adolescent ewes either overnourished to putatively restrict fetoplacental growth (n = 27) or control-fed (n = 12). At 131d (term = 145d) pregnancies were interrupted and fetuses classified as FGR (n = 17, Non-FGR > FGR and fetal:placental weight ratios were higher in overnourished versus Control groups. COT vascular indices were Non-FGR > FGR > Control. COT-CAD, CSD and APC were significantly greater in Non-FGR overnourished versus Control and intermediate in FGR groups. CAR vascularity did not differ. CAR- VEGFA/FLT1/KDR/ANGPT1/ANGPT2/SLC2A1 / SLC2A3 mRNA was lower and COT- ANGPT2 higher in overnourished versus Control groups. Discussion Relative to control-intake pregnancy, overnourished pregnancies are characterised by higher COT vascularity, potentially a compensatory response to reduced nutrient supply, reflected by higher fetal:placental weight ratios. Compared with overnourished pregnancies where fetal growth is relatively preserved, overnourished pregnancies culminating in marked FGR have less placental vascularity, suggesting incomplete adaptation to the prenatal insult.