A spokeswoman for the couple confirmed on Wednesday: "Zara and Mike Tindall are happy to announce the birth of their third child, Lucas Philip Tindall." The baby was born at the couple's home in Gatcombe Park on Sunday 21 March, weighing 8lbs 4oz.
Mike also announced the news on his podcast, The Good, The Bad & The Rugby, revealing that his son was born on the bathroom floor.
WATCH: Mike Tindall announces birth of baby boy
"Sunday got even better because a little baby boy arrived at my house," Mike said. "Arrived very quickly. Didn't make it to hospital. On the bathroom floor. So yeah, it was running to the gym, get a mat, get into the bathroom, get the mat on the floor, towels down, brace, brace, brace."
Mike revealed that Zara's friend Dolly, who was also present at the birth of their two daughters, recognised that they wouldn't have time to go to hospital. "Fortunately the midwife who was going to meet us at the hospital wasn't that far away so she drove up just as we had assumed the posit (position) and the second midwife arrived just after the head had arrived," Mike added.
Zara, who is the Queen's eldest granddaughter, and Mike are already the proud parents to two daughters – their firstborn Mia, who is seven, and Lena, who turns three in mid-June.
The Queen and Prince Philip also released a statement on Wednesday, via Buckingham Palace, saying: "The Queen and The Duke of Edinburgh are delighted with the news and look forward to meeting their 10th Great Grandchild when circumstances allow."
The Queen is "delighted" for her granddaughter
Mike and Zara's son's full name is Lucas Philip Tindall – with Philip in honour of both Mike's father as well as Zara's grandfather, Prince Philip.
Lucas's birth comes just a few weeks after Zara's cousin Princess Eugenie welcomed her son August with husband Jack Brooksbank on 9 February. Eugenie and Jack also chose to have Philip as a middle name for their baby boy, in tribute to the Duke of Edinburgh.
Mike had previously revealed he would like to have a boy. In December, he announced his wife's pregnancy on his podcast The Good, The Bad & The Rugby, telling his co-hosts James Haskell and Alex Payne: "It's been a good week for me, had a little scan last week – third Tindall on its way.
"I'd like a boy this time, I've got two girls, I would like a boy. I'll love it whether a boy or a girl – but please be a boy!" To groans from one of his co-hosts, Mike then joked, referencing the pandemic: "We're not sure what to do, Covi or Covina – I don't know where to go with names."
Zara and Mike are already proud parents to daughter Mia and Lena
In an interview with The Times, the doting dad also confirmed that he and Zara would be keeping the baby's gender a surprise. "It was always an interesting question whether we'd go for a third and I think both of us wanted a boy, so hopefully we'll get one," he said.
"We're not finding out – I think it's better that way. At the end of the day, you're just happy if it's got ten fingers and ten toes and it's healthy. And Mia's such a Daddy's girl, it's been brilliant. I've loved having girls."
The royal couple were married in Scotland in July 2011
Zara and Mike married in July 2011 in Edinburgh, Scotland and are preparing to celebrate their tenth wedding anniversary this summer. In the same interview, the sports star publicly spoke of his love for his wife, as he said: "She's always been my best friend. That doesn't change."
When asked by the newspaper what the secret to a happy marriage is, Mike responded: "I don't know if I've got any top tips. She's always right, is that a top tip? I think there's a lot of balance.
"It's always been good for us being two professional sportspeople. It's a bit clichéd but you understand each other, what your motivations are. I think that's why we gel."
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