With the clips...
When you are pregnant, the fallopian tubes swell. If you have the tubes only tied off with the clips within the first 5 or 6 months postpartum, the chances of becoming pregant are much greater than if you wait until after that 6 mo mark. It can take 6 mo for the swelling of the the fallopian tubes to go down..and...if the clips aren't tight enough...plus the swelling goes down...you end up with a passage way for pregnancy again.
I know a number of women that had their "tubes tied" immediately following c-section or child birth and still got pregnant. Using the clips only is a good way to do it if you aren't 100% sure...or if you think there is any chance you might change your mind years down the road. But ultimately, if this is the only procedure that is being used, it's best to wait that 6 mo or so.
DenMother Kat, RN...BScN, BA (Kin, AT), TNCC