I have had 2 previous c section and am pregnant now. is it possible for me to wait for an elective c section at week 40.if i wait that long won't i have complications? can't it be done early like 38 weeks?

The timing of elective C-sections at 38 weeks is standard. At that point spontaneous labor is less likely to push an urgent C-section at 3AM than waiting until 39 or 40 weeks. Assembling a surgical team at off hours adds risk. The baby's system ready for birth at 38 weeks so scheduling it then or soon after with a full regular team is prudent.

Your doctor should tell you if there is a need for earlier delivery, but in normal circumstances waiting until 40 weeks will not risk more complications. 39 weeks is generally the earliest that elective planned C-sections are done to minimize the risk of the baby having any problems due to prematurity.