Objective: Pregnancy is associated with physiologically reversible but important changes in various body systems like blood pressure regulation or oxidant status in various organs. The effects of transient hypotension on the fetus and mother are not studied extensively although experienced frequently. During hypotension, blood flow of many tissues is altered. The liver is vulnerable to hypoxia and the affected oxidant balance may lead to changes in other tissues, including the blood. On the basis of these accumulated data, in the present study we tested the effects of transient hypotension on oxidant stress in the liver in pregnant rats.