Endocrine modulation of uterine blood flow in pregnancy.

Uterine blood flow increases 15- to 20-fold during pregnancy. The fact that pregnancy is also characterized by dramatic increases in the production rate and plasma concentrations of estrogenic and progestational sex steroids has prompted investigators to explore a cause and effect relationship between these endocrine and physiologic changes. This article reviews the evidence that pregnancy-related increases in uterine blood flow are, at least in part, sex-steroid induced.