Increased Glucocorticoids in Pregnant Rats Reduces Fetal Growth and Placental Vascularisation

Healthy placental vasculature is critical for appropriate fetal development and health outcomes. Understanding placental vascular morphology and fetal growth is crucial for developing future diagnostic approaches. This study aimed to investigate impacts of glucocorticoids on fetal growth and placental vascularisation. 20 time-mated Wistar rats were administered with either vehicle or 0.5 μg/ml dexamethasone acetate (DEX, a synthetic glucocorticoid), via drinking water from embryonic day 13 until the end of the experiment. Dams were then euthanised for tissue collection. Fetal and placental growth were assessed using weight and morphometric measures. Individual feto-placental arterial vasculatures were cast with Microfil. Then 3D high-resolution micro-CT images of the casts were reconstructed and then were visualised and analysed using Amira and Matlab. Fetal and whole placental weights in DEX-treated rats were decreased by 14.09% and 34.12% respectively (p<0.0002). Additionally, labyrinth (inner) and junctional (outer) placental weights were decreased in DEX group by 30.31% and 41.98% respectively (p<0.0001). Maternal DEX treatment significantly reduced fetal and placental sizes (p<0.001). The 3D micro-CT data showed that placental arterial vascularity and complexity were decreased in DEX treatment relative to controls. Our data confirms that maternal DEX treatment impairs fetal and placental growth. Further studies are on-going to investigate in-vivo placental function by using the non-invasive MRI and to determine how MRI outcomes correlate with placental vascular structure.