The 'Smile' singer took to her Twitter account to give her fans an update of her condition, and joked that her baby bump had grown to make her feel like the waddling aquatic flightless bird.
"I feel like a penguin, not the chocolate covered biscuity kind, but an actual penguin that waddles," she wrote. "Now can't stop thinking about chocolatey penguins doh! (sic)"
She had previously tweeted on Sunday: "I can't see my toes and I'm not bendy anymore."
Allen married Sam Cooper at a ceremony in June, where the couple announced her pregnancy.
Allen and Cooper lost their first baby six months into her pregnancy last November. She previously miscarried the child she was expecting with Chemical Brothers star Ed Simons in January 2008.
The singer recently hinted at a return to music with a country album.
Watch the video for Lily Allen's 'Not Fair' below: