The goal of this observational study is to reveal the relation between carotid flow changes and post-spinal hypotension in pregnant women between the ages of 20-40. The main question it aims to answer is: Do the carotid flow blood flow measurements and corrected flow time change before and after spinal anaesthesia related to postspinal hypotension? Participants are already receiving spinal anaesthesia to receive a caesarean section. As part of their regular anaesthesia management protocol, they will answer questions about anaesthesia management. The participants will only examined by ultrasound twice.