A representative for the 29-year-old Fifty Shades of Grey star told PEOPLE that Johnson is not pregnant. The representative said the blue and pink balloons spotted at Martin's home on Sunday were for her birthday party.
The statement follows a report from TMZ, which posted photos of the pink and blue balloons, as well as the celebrities arriving at the event. Johnson's parents — actors Melanie Griffith and Don Johnson — were seen at the party, along with Sean Penn and Julia Roberts.
TMZ reported that about 10 minutes after Don Johnson arrived, the string of blue balloons was released into the sky, hinting that the couple was having a baby boy.
Martin, 41, and Johnson, 29, have reportedly been dating for a year. The Coldplay singer was previously married to Gwyneth Paltrow for 13 years and share two children, Apple, 14, and Moses, 12. The couple's divorce was finalized in 2016.
Less than two weeks ago, Paltrow married American Horror Story producer Brad Falchuk at her East Hampton home. Robert Downey Jr., Jerry Seinfeld, Cameron Diaz and Benji Madden were among the guests.
Johnson and Martin have been very private about their relationship.
"I'm not going to talk about it. But I am very happy," Johnson told Tatler.
While the two stars have avoided commenting on the relationship themselves, Griffith recently gushed about Martin, reports The Daily Mail.
"I adore him! But she is very private about her life and I respect that," Griffith said of Martin.
"He's a lovely guy. I've met him and you want your kids happy, no matter what shape it takes," Don Johnson added. "That's the goal, that's the key. He's a very talented and gifted musician. I've seen them in a concert at a small venue called the Troubadour in Los Angeles when they were first coming out and that was a memorable moment. I knew right then he'd be good for her. I said, 'Oh you know, that man has got something going on.'"
A source also told PEOPLE recently that Johnson "seems to love hanging out" at Martin's Malibu home.
"They occasionally go for dinner with friends, but mostly have friends over at home," the source said. "They go to the beach together, and walks around the neighborhood. They seem to enjoy sharing a quiet life. It does seem they are getting more serious."
Johnson will next be seen in Suspiria, which opens on Oct. 26. She also stars in Bad Times at the El Royale, which opens on Oct. 12.
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