The former Lizzie McGuire star announced in August 2011 that she and husband Mike Comrie are expecting their first child together later this month.
Posting on her Twitter page on Friday (March 16), Duff expressed her impatience to give birth as well as her frustration with her ever-increasing size.
"Ok! no joke.. When i get up my massively pregnant morning walk looks like a "walker" from "the walking dead" #cmooooon BABY (sic)," she wrote.
In February, Duff posted a photograph of herself and Comrie on Twitter, displaying her baby bump at its largest.
Duff has confessed that she is a little afraid of motherhood, saying: "Anything that's unknown is scary to us, and I'm definitely a little afraid. It's not something you want to mess up and it's not something to take lightly."
> Hilary Duff's husband Mike Comrie retires from hockey