Simon Cowell -- Babies Can't Hold Me Down, I'm on a Boat!

No fetus is gonna slow Simon Cowell's roll -- the "X Factor" judge is still partying his ass off on a yacht in the French Riviera ... with bikini-clad women ... while his pregnant baby mama is waging her divorce war back in New York.

A shirtless Simon and his mystery blonde were photographed just hours ago, soaking up the rays on France's Mediterranean coast ... not a care in the world.

Meanwhile, Simon's baby mama Lauren Silverman is toughing out nasty divorce proceedings with her estranged husband.