A dynamic reservoir for blood volume, the venous system possesses a virtual point of conversion between unstressed volume (Vu) and stressed volume (Vs). Understanding the physiologic implications of this conversion during pregnancy, particularly as it relates to the maternal and fetal consequences of hypotension (e.g. supine and neuraxial technique-induced), hypertension (e.g. preeclampsia), and fluid administration (e.g. early recovery after cesarean delivery protocols), provides opportunities to understand and develop clinical options (Table 1).