The local actions of glucocorticoids in the placenta can be modulated by 11β-hydroxysteroid dehydrogenase (11βHSD) enzymes, which catalyse inter-conversion of cortisol with its inert metabolite, cortisone, and are known to be expressed in the term placenta and decidua. However, the expression and activity of these enzymes have not been well characterised in the first trimester placenta. The aim of this study was to compare 11βHSD2 expression and activity in first trimester placental tissue from pregnancies at either relatively low or high risk of developing pre-eclampsia as determined by Doppler ultrasound.