Sarah Hyland, who plays Haley, shared another surprise on her Instagram after the episode aired.
"Well I guess the cat’s outta the bag!!! Or more like the bump’s outta the shirt!..... that was a horrible joke. I apologize," she wrote in the caption for a behind-the-scenes selfie showing off her fake baby bump for the show.
Adams even celebrated the (fictional) news on his Instagram Story.
"Whaaaat? I'm so happy! Is it mine?" he jokingly asked in the video
She also told fans that she was aware of the plot point well before the season started, but didn't know exactly how it would happen.
"I had zero information on details!" she wrote.
Haley's pregnancy news is the latest shift in Modern Family's storytelling. Last week, during their Halloween episode, the series said goodbye to Claire and Mitchell's mom, Dede Pritchett (Shelley Long), revealing her character had died.
The episode even brought Hyland to tears, given how close she is with her onscreen family.
“I thought it was an amazing episode. It made me cry,” Hyland told ET at the No Kid Hungry event in Los Angeles, California, on Friday. “Ed O’Neill is just so brilliant. He always makes me cry. There’s just something about an old man crying that gets me. And, especially when it’s my grandpa.”
The news of a character death was announced in September, with co-creator Christopher Lloyd telling EW that the cast would be "handling some bigger life events."
Modern Family airs on Wednesdays at 9 p.m. ET/PT on ABC. See more in the video below!