REN and hypertensive disorder: There is some debate about the pathogenetic mechanism; the initial hypothesis that still stands is the so-called unifying pathway by Woods [46], according to which environmental and placental factors, such as maternal protein restriction, alterations in the placental or uterine circulation, or placental insufficiency, which all determine low birth weight, may cause hypertension in adulthood due to activation of the renin-angiotensin system as a consequence of a low number of nephrons.