[Possible involvement of the renin-angiotensin system in reproduction. III. Occurrence and role in pregnancy].

To clarify a possible participation of the renin-angiotensin-system (RAS) in physiological processes of pregnancy, findings are listed about occurrence and variations of RAS components in uterus, placenta, amniotic fluid, fetal membranes, fetus and serum. There exist complete and independent RAS in the respective organs and tissues. During pregnancy concentrations and/or activities of the components change, but in different ways and non-uniforming. The information now available does not yet allow a definite view on the role of RAS during pregnancy and on the correlations to estrogens, progesterone, chorionic gonadotropin, prostaglandins etc. Supposedly RAS may be involved to a high degree in the local regulation of blood flow and the maintenance of fetal vascular homeostasis. Furthermore, there are relations between fetoplacental components of RAS and pregnancy-induced hypertension. Further investigations are necessary. They are expected to offer therapeutic possibilities for influencing pathological processes in which RAS plays a role.