Women indicating that they had been in labour for 24hours or longer at the time of hospital admission were at elevated risk for cesarean birth , relative risk ( RR ) 1.40 , ( 95 % Confidence Intervals 1.15-1 .72 ) , admission with a cervical dilation of 3cm or less , RR 1.21 ( 1.07-1 .36 ) , more obstetrical interventions including continuous electronic fetal monitoring RR 1.11 ( 1.03-1 .20 ) , augmentation of labour RR 1.33 ( 1.23-1 .44 ) , use of narcotic RR 1.21 ( 1.06-1 .37 ) and epidural analgesia RR 1.18 ( 1.09-1 .28 ) .