There's a framework for a fun comedy here, but no one says anything witty and none of the characters emerge as anything resembling a real person with bigger problems than the kind of babies-are-a-handful stuff that Erma Bombeck once built a career out of.
It's never a good sign when the supporting cast is the most interesting thing about your movie, but when your supporting cast is almost the entire cast of Bridesmaids (minus Melissa McCarthy), it's almost inevitable.
Friends with Kids doesn't really understand kids very well. It also doesn't understand the friends. This entire world is about Julie and Jason. And even then, their neurosis and emotional entanglements seem a bit too... written.