Hep-B Vaccine At Birth?

Hi everyone!

To start this off, this is NOT an anti-vax discussion. I just want to hear from others as I am a FTM.

Why are Hep-B vaccines given at birth even if you are negative for Hep-B/not in any situations that your infant may be exposed to Hep-B? I am aware that it is safe and recommended - but WHY at birth?