Norwegian has the similar “Grådighetspause”, “greed break”.
I’m curious if there are cultures that don’t feel the need to fill the silence.
I’ll sometimes say “Chatkill”, but that’s more of a misplaced internetism, and I will sometimes make the “Awkward Turtle” hand gesture, depending on who is in the conversation.
Basically, Hold both hands in front of you, one laying over the other. Wag your thumbs so it vaguely resembles a turtle swimming. Depending on how awkward the pause is, or how silly I’m feeling, I’ll make the turtle swim faster and faster until my wife makes me stop.
My grandpa used to say “Let’s not all talk at once.” An occasional variation was “Must we put up with this ceaseless chatter?”
In my group of friends it was “Abraham Lincoln.” That is, when a sudden silence fell over a group, we’d say “Abraham Lincoln” as in, somebody is thinking of Abraham Lincoln. No, I have no idea where it came from either, but it was true. Upon learning this little game or whatever you want to call it, whenever a silence fell over a group, I, at least, was thinking of Abraham Lincoln.
Could that be a pregnant pause?
One might say “Refill, anyone?”
“No one has anything nice to say?”
What do you say when silence falls over a group?
Based on my previous history, something inappropriate at that exact moment.
I’d probably go with my old standby;
“How `bout those Carolina Hurricanes* this season?”
It opens the door for someone else to say something. Sure, it’s off-topic, so there’s some comic relief from using it, too.
So, it’s not hockey season. That doesn’t matter because when I use it I’m obviously/purposefully trying to change the subject or disrupt the flow of the conversation. Works most every time, btw.
*(Or Pittsburgh Penguins or Dallas Mavericks or NY Yankees)
“Have any of you heard of Multi-Level Marketing?”
How about those Warriors?
This is fun, but I do think the OP was asking for what this specific phenomenon is called, not how we react when it happens.
The best I’ve got is ‘‘a lull in the conversation.’’
“That concludes today’s sermon”.
My culture (Finns) enjoys silence. There’s usually some talk going on if there’s a big dinner party but if silence does happen it’s no big deal. We do get awkward silences too but that’s more of a thing with people who don’t know each other that well, if I’m somewhere with friends or relatives any silences are perfectly comfortable and natural.
“Sooooo…Anyone hear about this Benghazi stuff?”
Carlsbad Caverns. Everyone sits down, and they turn out the lights.
Total darkness.
Total silence.
I said, not loudly, but loudly enough to be heard clearly, “Get your hand out of my pocket, sir…”
(I was young…)
Huh. Apparently, it’s not just my group of friends who did this. (Unless that Urban Dictionary entry was put up by one of my friends, of course.)
I would fit right in. Some people just cannot handle silence, and have to fill it with anything they can think of. I really don’t mind.
I always fall back on, “Somebody tell a joke!” And somebody usually does.
I’ve tried “Are we having a Quaker Meeting?”* but it always falls flat. 
*Stands on its own, but is a reference to “Little Town on the Prairie,” Laura Ingalls Wilder.