The 31-year-old singer broke the baby news in an interview with Britain's OK! Magazine, admitting it came as something as a shock considering they welcomed daughter Aurelia into the world just 11 months ago.
"I don't know if I'm prepared for it! Aurelia has been a whirlwind and all of a sudden we've got another baby on the way!" he told the publication.
Kelsey added that she was less surprised by the pregnancy, and explained: "I had stopped breastfeeding Aurelia, and that can make you more vulnerable to getting pregnant. I want a big family so I would rather just get it over and done with. I'd like to have three or four, but I don't know how Tom feels about that."
Tom and Kelsey first met in a nightclub in 2009, and married in July 2018.