Polypregnancy is one of the major problems to both mothers and fetuses leading to poor prognosis. Even though hemodynamic parameters change greatly during pregnancy and cesarean delivery, it is unclear how blood volume (BV) and cardiac output (CO) increase during triplet pregnancy and how CO goes up and down during cesarean delivery in the cases of triplet pregnancy. We measured BV and CO by dye-densitogram analyzer (DDG-analyzer: Nihon Kohden, Tokyo, Japan) and CO by FlowTrac (Edwards Lifesciences, Irvine, USA) on three cases of triplet pregnancy. BV increased up to about 50% above that of singleton after 20 weeks of gestational age. However, there was no such tendency in CO. When they underwent cesarean delivery under combined spinal-epidural anesthesia (CSEA) or sequential-CSE (S-CSE) receiving a 10 or 12 mg intrathecal isobaric bupivacaine with 20 microg fentanyl, CO decreased in parallel with blood pressure from ten minutes after spinal anesthesia, to the start of operation and just after the birth of third fetus.