To have a bun in the oven is a slang term for being pregnant or conceiving. If a woman has bun in the oven, this means that she’s pregnant. In this context, the bun is the baby and the oven is the woman’s body or the womb.
You can also use “they”, referring to a couple who are expecting a baby.
Let’s see some examples :
– Congratulation! Your wife has a little bun in the oven.
– My pregnancy test is positive. I guess I’m going tohave a bun in the oven.
– Rocio has a bun in the oven. I hope that baby isn’t mine.