I had an anterior placenta which moved low the week prior to delivery and ending up being placenta previa. My Ob was still able to do the c/s with the cut being low (they didn't know how low the placenta was until delivery), but as it was anticipated that I would have palcenta previa they did blood matching prior to the procedure to make sure they had blood on standby if needed. To get DD out my Ob had to cut through the placenta and in total I lost about 500mls of blood, even though this is higher than normal it was not extreme and I didn't need a blood transfusion after all.