Pregnancy make demands upon maternal calcium hemeostasis and the extent to which the maternal bone mass is effected remains uncertain. Recently changes in the bone mass during human pregnancy have been associated also with the transformation of the cancellous architecture and the bone surface available for exchange. These jistomorphometrical structural changes were examined further in an animal model.

          Using uniparous laboratory rats fed at libitum, the histomorphometry of cancellous bone was compared in undecalcified of caudal vertebrae. Between 3 and 6 sections (8 mm) were analysed by an automated trabecular analysis system (TAS) which measures a comprehensive range of structural variables including the trabecular separation, number, connectivity and width.

          There was an early stimulation of bone formation that was indicated by generation of thicker and interconnected trabeculae. However in caudal vertebrae, there were architectural changes in cancellous bone commencing with a significant increase in the trabecular separation. ‌‌

          It was concluded that strengthens the cancellous component of the maternal skeleton possibly to counter increased load and to facilitate mineral mobilisation in maternal/neonate exchange during the subsequent lactation period.