Aging of the placenta.

Introduction It is widely believed that during the relatively short duration of a normal pregnancy the placenta progressively ages and is, at term, on the verge of a decline into morphological and physiological senescence. This belief is based on the apparent convergence of clinical, structural, and functional data, all of which have been taken, rather uncritically, as supporting this concept of the placenta as an aging organ with, all too often, no distinction being made between time related changes and true aging changes. I will review some of these concepts and consider whether the placenta truly undergoes an aging process. For the purposes of this review an aging change is considered to be one which is intrinsic, detrimental, and progressive and which results in an irreversible loss of functional capacity, an impaired ability to maintain homeostasis, and decreased ability to repair damage.