The 35-year-old recently penned a column for Waitrose Weekend last month, Pippa explained how she has been keeping fit during her pregnancy.
'Swimming throughout pregnancy offers a wonderful feeling of weightlessness,' she wrote.
'From personal experience, I'd confidently say I find it has been the most enjoyable and rewarding form of exercise since I found out I was expecting.'
Earlier this week, Pippa also announced she is teaming up with the Mary Hare Primary School Appeal alongside sculptor Sophie Ryder to sell 50 limited-edition bronze hare sculptures.
The sculptures will aim to raise enough money to build a brand new national primary school for deaf children.
Speaking of the new project, Pippa admitted her pregnancy has shifted the way she thinks of charity work.
'The idea came to me as I was trying to find a way to use the 'Hare' animal as part of an art charity fundraising project for the school,' she says on the campaign website. 'Typically I would opt for a sporting challenge to raise money but being pregnant this was a little harder to achieve.'
Pippa has been an ambassador for Mary Hare since 2013. Not long after her wedding to James Matthews in 2017, Pippa launched an appeal for a brand new building, saying at the time: 'There are many good reasons to support the Primary School project and I am delighted that the appeal launch has been so successful.'