The anaemia and hydraemia of pregnancy in the Norway rat, Rattus norvegicus .

Abstract

First paragraph: The physiology of pregnancy is a complex and extensive field in which the majority of those working with animals other than man have confined their research and observations to hormones. It is the human subject which has been the most studied in the wider aspects of the general physiological change which occurs during gestation. Following the now classical work on the oestrous cycle of the rat by Long & Evans in 1922, a small number of papers have periodically appeared on various physiological aspects of the oestrous cycle and pregnancy. In 1929 Sure et al noticed that a drop in the concentration of red cells occurred in the blood of the rat on the last day of gestation. They attributed this anaemia to haemorrhage at parturition and to dietary factors. Later work by other authors showed that the anaemia could be attributed to the effects of gestation, particularly the placenta, and was not the product of a deficient diet. Various theories were mooted for the basic mechanism of the anaemia and for its hormonal source, some suggesting an hydration of the blood (hydraemia), thus increasing the plasma volume, others suggesting an increase in blood volume with a disproportionate increase in plasma volume and yet others to a decrease in erythropoiesis0 By 1950 the work on this aspect of reproductive physiology had apparently stopped, perhaps because of the greater 2. interest in hormones. Recently further work has been done on the anaemia of pregnancy in the mouse (Fruhman, 1968; Rugh & Somogyi, 1969).