Mostly very safe
Provided the surgeon, pediatrician, obstetrician or mohel is well trained and careful.
I believe plastibell method, where the redundant foreskin
is tied off over a small plastic ring is the safest because risk of bleeding is very slight.. Correct size plastibell ring must be selected and a frenular bleed should be cauterized.(check google.Com). Clamp method usually safe, but risk of bleed more.