A spokeswoman for Pippa Middleton and her husband said the couple’s baby was a boy born on Monday.
She said: “James and Pippa have had a baby boy.
“He was born Monday 15th October at 1.58pm, weighing 8lb and 9oz. Everyone is delighted and mother and baby are doing well.”
Pippa and husband James Matthews were seen arriving at the private maternity wing of St Mary’s hospital in London on Monday according to reports.
The news follows the Duke and Duchess of Sussex’s announcement they are expecting their first child.
Kensington Palace said in a short statement: “The Duke and Duchess of Cambridge are thrilled for Pippa and James.”
Pippa and Kate's brother James Middleton was the first to visit the new family member, who was born at the Lindo Wing in London - the same place where Kate's children, Prince George, Princess Charlotte and Prince Louis were born.
In the lead up to the exciting news, Pippa – who is married to 42-year-old husband James Matthews - shared the tips that helped her through the final weeks of pregnancy.
She had been keeping her fans up to date about her pregnancy progress through her fitness column for Waitrose.
She recently wrote: “As the final month nears and the bump grows prouder each day, movement is certainly getting more awkward.
“As a result, one of the biggest changes is that my lower body has tightened up.”
"I signed up to a beginners’ meditation class recently to master the tools essential for performing it effectively," Pippa also revealed.
"This involved learning to meditate twice daily, ideally for 20 minutes, chanting a mantra, while sitting upright, eyes closed and focused...
"Our teacher stressed that we should ensure we always make time for this because there’s always an excuse not to."
Pippa went on to say that the idea of the ‘meditation window’ is to take your mind and body into a state of ‘pure rest’.
"Most importantly, it allows an opportunity to restore and nourish both mind and body.
"I was sceptical at first — but, after practising this discipline for the past month, I have noticed a huge difference in my mental wellbeing and sense of clarity," Pippa revealed.