Eva Longoria's comfortably embracing her 4-month-old baby bump to ring in the new year ... in PJs, no less.

The "Desperate Housewives" star posted her first public photo of her pregnant belly Monday with the caption ... "New year, new adventures! I’m so grateful to my beautiful family for giving this new baby so much love already! #HappyNewYear #2018."

As we reported ... Eva and her hubby, Jose Baston, are expecting their first child together -- which would be Eva's first baby ever. Her rep confirmed she's preggo with a boy.

Looks like the kid's gonna be welcomed with open arms. Congrats!