The younger sister of Kate Middleton welcomed her first child with husband James Matthews in October

By Stephanie Petit
April 19, 2019 11:41 AM

Pippa Middleton is passing her passion for sports onto her son!

The younger sister of Kate Middleton opened up about being a mother to 6-month-old Arthur for the first time in U.K. supermarket monthly Waitrose Kitchen magazine. After previously sharing how swimming helped her stay fit during pregnancy, Pippa revealed that Arthur is already loving the water.

“Starting my son Arthur swimming at four months old has given him confidence and enjoyment in water,” she wrote, according to the Instagram fan page MiddletonMaven. “He’s now six months old, and swimming is one of our favorite activities. The exercise helps guarantee sound daytime sleeps, and the movement has improved his digestion.”

David M. Benett/Getty

Pippa added that swimming is fun for both mother and son: “Water activity is a great form of exercise you can do with your baby.”

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Pippa Middleton in February
The Image Direct

Pippa, 35, previously said swimming had become a go-to way to keep up her fitness routine as she neared her due date.

“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,” she shared. “It’s comforting to know that it’s safe throughout pregnancy, and you don’t need to adapt and change too much (unlike most other sports). It’s so good for you that you could swim every day – as long as you don’t overexert yourself – right up until the end of the third trimester.”

James Matthews and Pippa Middleton
Pool/Samir Hussein/WireImage

Pippa and husband James Matthews have been spotted around London and on vacation in St. Barts since becoming parents, but she made her first official post-baby outing at a charity gala event in late February.

A source previously told PEOPLE that Pippa and James are looking forward to settling down and “having children and leading a quiet life.”

Pippa Middleton
Splash News

Of course, soon Prince George, Princess Charlotte and Prince Louis will have another cousin as a playmate: Meghan Markle and Prince Harry are expected to welcome their first child in the coming weeks.