Pregnancy and lactation make demands on maternal @entity460 homeostasis which may affect bone strength. Recently, changes in cancellous architecture have been described in iliac crest bone biopsies from normal pregnant @entity1 but the rarity of such @entity1 material means an animal model is essential. The microanatomy of cancellous bone was compared in uniparous and multiparous @entity35 using undecalcified histological sections of lumbar and caudal vertebrae and also proximal femora. An automated @entity652 ( @entity652 ) measured a comprehensive range of structural variables including the trabecular number, connectivity and width. In the first pregnancy cycle an early stimulation of bone formation (which quadrupled at some sites) was indicated by an increase in the skeletal uptake and spacing of double calcein labels and the immediate generation of thicker more numerous and interconnected trabeculae. A 40% increase in cancellous bone volume was observed in the lumbar spine in comparison with age-matched virgin controls. In contrast, a rapid succession of 3 pregnancy cycles (including lactation) culminated in cancellous @entity194 of 15% at the same site, with a loss in trabecular number ranging from 20% (caudal vertebra) to 30% (lumbar vertebrae). In comparison, the proximal femur lost 40% of its struts but, nevertheless, uniquely sustained its cancellous bone volume. When lactation was excluded the number of struts lost was halved although trabecular thinning then took place which was sufficient to maintain the previous 15% deficit in bone volume. It was concluded that a single pregnancy strengthens the cancellous component of the maternal skeleton while a quick succession of pregnancies weakens it. Lactation influences the pattern of @entity604 but not its amount.

The impact of XXXX reproduction on cancellous bone architecture.

@entity1 :: ('9606', 'Species') :: ['women', 'human'] @entity604 :: ('MESH:D016301', 'Disease') :: ['bone loss'] @entity194 :: ('MESH:D001284', 'Disease') :: ['atrophy'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity35 :: ('10116', 'Species') :: ['rats'] @entity652 :: ('MESH:D000236', 'Disease') :: ['trabecular analysis system', 'TAS']
@entity1 :: (9606,Species) :: ['mammalian']
