Rheological Studies in Obstetrics and Gynaecology

Because of the strong connection between arterio-venous thrombo-embolism and oral contraception (Vessey and Mann, 1978) much interest has been focussed on the alterations in rheological parameters caused by hormonal ovulation suppression. A full understanding of these effects of oestrogens and progestagens must be based on a sound appreciation of the physiological background upon which they are imposed but little attention has been paid, as yet, to the rheological changes in the menstrual cycle and pregnancy. In common with most biological measurements rheological parameters vary in response to circadian (Seaman et al., 1965), menstrual (Dintenfass and Yu, 1968) and reproductive (Hamilton, 1950) cycles. This chapter is a review of the existing literature on rheological changes during ovulatory cycles, oral contraception and pregnancy, supplemented by our own data drawn from serial and cross-sectional studies of women in these various states.