The 35 study pregnancies yielded 6-month Kaplan-Meier cumulative typical use pregnancy probabilities per 100 women with 95 % confidence intervals ( CIs ) of 10.4 ( 6.9-14 .0 ) for all users and 9.6 ( 5.5-13 .6 ) and 12.5 ( 5.4-19 .5 ) with acid-buffering gel and nonoxynol-9 , respectively .