have a bun in the oven

/HH AE1 V AH0 B AH0 N IH0 N DH AH0 V AH0 N/
verb
  1. 1

    To be pregnant; to be expecting a baby.

    โ€œHer parents were surprised to learn that she had a bun in the oven.โ€

Source: https://en.wiktionary.org/wiki/have%20a%20bun%20in%20the%20oven