The hard-hitting storyline will begin on New Year's Eve when Ronnie Mitchell discovers that her newborn son has died and swaps him with Kat (Jessie Wallace) and Alfie Moon's (Shane Richie) baby.
The Sun reports that the scenes will show Ronnie (Samantha Womack) hold her child's blue fist and touch his face with the back of her hand.
"It's high drama, which EastEnders has a 25-year history of delivering," Kirkwood said. "We deliver big, big, gritty stories that chime with the audience, and I think that's what these stories do. It's undoubtedly a bold storyline. I'm very proud of the episodes."
The former Hollyoaks boss said that the show had worked to ensure the scenes had an "absolute believability" to them.
"We went to great pains to see that the babies are born in different circumstances and we took advice from a maternity nurse on how the story could come about in real life," he stated. "We started the story-planning by asking, 'How could this happen?' I think there is an absolute believability to how the events unfold."
He added that the dark plot will be balanced out with scenes of celebration as the Walford residents welcome in the New Year.
"We took great pains to make sure the rest of the episode showed a community with a lot of love," he said. "We see a lot of friendships, fun and festivities, and we hope these counter the inevitable darkness of this story."