I’ve just come across this phrase for being pregnant on another forum, used by someone from the UK. Google turns up a few hits. Is anyone else familiar with it, and how recent is it?

Are you sure it was used to mean “pregnant”? Jonathon Green’s Cassell’s Dictionary of Slang (2e) has as sense 3 under “doughnut” n. “[1980s] of a woman, a state of sexual excitement, supposedly the vaginal equivalent of the penile erection.”

Green’s work is not always reliable, though. If you want to get an idea of how he can go wrong, look under all the entries for “doughnut” and you’ll find “doughnut” v. “[1970s+] (Aus./US teen) to make an automobile spin by pulling on the hand-brake. The vehicle in question is usu. stolen.”

There are at least three things wrong with that. One, there’s no entry for the noun form of the verb, which is far more common in the US. We’d say “do a doughnut/make doughnuts/do doughnuts.”

Two, it’s not always nor, in my experience, most often done with the hand-brake. The definition is overly specific and needs to be more general.

Three, “usu. stolen” is ridiculously overly specific and most likely wrong, too boot. Again, the definition needs to be more general.

I’ll have to ask Green the next time I see him if his entry is merely a memory of his own youthful shenanigans (though he’s British) and not gathered from citation evidence. Joshing between lexicographers makes dictionaries better. :)

Googling turns up only 8 distinctive entries (i.e., with the duplicative hits suppressed)for “hanging a doughnut”.  One is this thread, a couple seem to refer to sports scores (doughnut = zero, I’m guessing without looking closely), one refers to actually hanging a doughnut from a string, and four refer to being pregnant.  None refer to sexual excitation.

Edit: If you spell it “… donut”, there are fewer hits, but all refer to pregnancy.

Never come across it in either context in any bits of the UK I frequent.

You can see the original exchange here. The person who used it did use the spelling ‘donut’, for what it’s worth, and none of the others on the thread (all British) had heard it either.

Given the paucity of Google hits, I’d say it’s a fairly rare expression on either side of the pond.  And FWIW I don’t see the logic behind it, either.