Cameron Diaz and Benji Madden Spark Pregnancy Rumors as She Covers Up

This video is unavailable because we were unable to load a message from our sponsors.

If you are using ad-blocking software, please disable it and reload the page.

Cameron Diaz and Benji Madden just can’t shake the pregnancy rumors.

A source tells ET that the latest baby rumors took off after the What to Expect When You're Expecting was seen covering her belly and drinking only water on a recent trip to Australia where her husband was taping The Voice alongside his brother, Joel.

WATCH: Benji Madden Wishes Wife Cameron Diaz a Happy Birthday

Diaz, 43, and Madden, 36, were flanked by photographers when they landed in Los Angeles on Monday who tried to coax the news out of the newlyweds by wishing them congratulations. The newlyweds kept quiet as they headed to their car, refusing to confirm or deny the rumors, but Diaz did hide her stomach with baggy clothes and a handbag. ET also reached out to Diaz’s rep who did not respond with a comment.

This follows Diaz's birthday on Aug. 30, which Benji celebrated in part by posting a selfie with a heartfelt caption.

"Happy Birthday to my Beautiful Wife," Madden wrote. "My best friend and Everything else - there's so much I could write. I'm the luckiest guy alive - I get to spend the rest of my life right here. I love this Woman!! Many more Baby!!"

WATCH: Newlyweds Cameron Diaz and Benji Madden Show Some Serious PDA Courtside

The couple tied the knot during an intimate ceremony at Diaz's Beverly Hills home on Jan. 5 after first being set up by Joel's wife Nicole Richie. Nicole and Joel wed in 2010.

Pregnant or not, Diaz has never looked better and she shared with British Vogue her secret to staying young.

"The fountain of youth [for me], let's see... I guess it's exercise, healthy diet, lots of water, lots of laughter, lots of sex," she told the magazine. "Yes, sex, we need that as human beings. It's healthy, it's natural, it's what we are here to do!"