Effect of lactation on blood volume in the human female

Abstract

T H E P u a P 0 s E of this paper is to present data regarding the effect of lactation on blood volume in the human female. The literature on blood volume changes during pregnancy is voluminous but largely descriptive. Etiologic factors remain unclear. Therefore, it is somewhat surprising to note the paucity of studies designed specifically to determine the relationship between lactation and blood volume. The review of the literature back to 1940 has failed to reveal any such study in the human female. Turner and Herman1 report a definite increase in total blood volume during lactation in dairy cattle. In the same subject, Reynolds2 found lactation to be associated with an increase in plasma volume to magnitudes of 25 per cent with the maintenance of normal hematocrits. Hansard and associates3 report an increased total blood volume with normal hematocrits in lactating burros. Bond4 has reported an increased red cell and plasma volume in lactating rats as compared to nonpregnant controls. He found that the hypervolemia returned to normal when lactation ceased. Bond also comments on the paucity of studies in this area and speculates upon an endocrine etiology for the findings described. Fifty-nine subjects were studied. Twenty-one women breast-fed their babies throughout the period of the study and are referred to as the study group. The control group consisted of 38 women who bottle-fed their babies throughout