 Anesthesia for cesarean section requires special importance because it may affect both mother and the baby. To avoid maternal hypotension related to spinal anesthesia must be the primary objective during anesthesia. Even though many factors influence sensory nerve block for surgical anesthesia, local anesthetic dose is the main determinant. Another factor that influence the sensory nerve block is the obesity related to pregnancy. Due to the enlargement of epidural venous plexus related to pregnancy, the subarachnoid and epidural space reduces, so the local anesthetic requirement also reduces. Many investigators recommend lower dose of local anesthetic in obese patients due to reduced requirement There are many studies about dose regimens for cesarean anesthesia, but ideal dose have not been found. Investigators have designed this study to see the effects of conventional dose 10 mg bupivacaine vs. low dose plus fentanyl 7,5 mg bupivacaine25 mcg fentanyl in obese and normal weight pregnant for cesarean section. The hypothesis was: the low dose regimen provides surgical anesthesia in obese patients while avoiding maternal hypotension. 