Louis Tomlinson: Hands-On Daddy Jetted to L.A. for Birth

Louis Tomlinson did NOT miss the birth of his first child ... TMZ has learned.

Our sources say the One Direction singer was at the L.A. area hospital when ex-gf Briana Jungwirth popped out their son on Thursday evening.

Louis was out in Beverly Hills Friday, making a quick stop at a sunglasses shop -- 'cause, really ... what's cuter than a baby in shades? The photog asked about a possible baby name, but Louis played it coy.

Briana's doing well and still at the hospital with the baby. We're told she's seen all the fake baby pics posted by 1D fans today, but rest assured ... they're all bogus.

Baby hasn't done any photoshoots. Yet.