Megan Fox In Case You're Wondering Who's the Daddy ...

4/12/2016 5:31 PM PDT

Megan Fox has been giving multiple clues on the identity of her baby daddy, and by process of elimination it's pretty clear ... Brian Austin Green is the leading candidate.

A noticeably pregnant Megan and her estranged hubby strolled into a Santa Monica restaurant Tuesday for lunch.  

It's relevant because earlier in the day Megan Instagrammed pics of 3 of her recent co-stars -- Shia LaBeouf, Will Arnett and Jake Johnson -- with the hashtag, #notthefather.

TMZ broke the story last August when Megan filed for divorce, but she's been cozy with Brian and their 2 kids recently, so it seems highly likely at the very least they're having their 3rd kid.