Saint West Gets His Papers ... Birth Certificate Revealed

Saint West has a lot in common with his big sister and his cousins ... that's besides DNA.

TMZ obtained a copy of the little guy's birth certificate, which was filed with L.A. County on Friday. Not a lot of shocking details -- no middle name, and it was signed last Monday ... 2 days after his birth.

He was delivered by Dr. Paul Crane, who also welcomed North ... and all 3 of Kourtney's kids. Best of all ... he even pulled Kim outta Kris Jenner 35 years ago!

The guy knows his way around a Kardashian hoo-ha.