Overall , 71 % of women experienced adverse effects during the first hour of their infusion ; the difference between groups was not significant [ 15/25 ( 60 % ) 60-minute loading ; 21/26 ( 81 % ) 20-minute loading ; risk ratio ( RR ) 0.74 ; 95 % confidence interval ( 95 % CI ) 0.51-1 .08 ] .