When you're eating for 2 ... ya gotta stock up!!

That's why Serena Williams hit the grocery store with fiance, Alexis Ohanian, and her mom Oracene Price this weekend ... and HAM in the aisles.

The gang rolled into Publix in Palm Beach Gardens (try the crab legs!) and filled their shopping cart to the brim in preparation for Serena's big day. 

By our count, she's about 37 weeks pregnant (40 weeks is the target) -- but at this point, it could happen any minute. 

Williams tweeted about how the pregnancy is affecting her body over the weekend -- "It's official. I no longer have ankles."

Still looks damn good to us.