06/08/2018 06:48 EDT | Updated 06/08/2018 06:53 EDT

Pippa Middleton Confirms She's Pregnant With Her First Child

The rumours have been swirling for weeks.

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Pippa Middleton arrives at St George's Chapel at Windsor Castle for the wedding of Prince Harry to Meghan Markle on May 19, 2018 in Windsor, England.

LONDON — Pippa Middleton is following in her sister's footsteps — she's about to be a mother.

The younger sister of Kate, the Duchess of Cambridge, revealed in the publication Waitrose the "happy news'" of her pregnancy and says she has passed her first trimester.

She is photographed working out and discusses how she has adapted her exercise routine to her condition. She promises to chronicle her pregnancy workouts as a columnist for Waitrose Weekend magazine, which is published by a British supermarket.

This will be the 34-year-old's first child. She married hedge fund manager James Matthews in 2017.

Pregnancy rumours had been swirling for weeks prior to Middleton's announcement, and royal watchers keenly observed her movements at the recent wedding of Prince Harry to Meghan Markle, now the Duchess of Sussex.

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Pippa Middleton and James Matthews arrive at St George's Chapel at Windsor Castle for the wedding of Meghan Markle and Prince Harry. Saturday May 19, 2018.: Chris Radburn/Pool via REUTERS

Middleton was spotted after the wedding at the French Open in late May:

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Pippa Middleton attends the 2018 French Open May 27, 2018 in Paris, France.

The tennis fan said about her first pregnancy in Waitrose, "I wanted to know things like, would I strain if I served in tennis, are all strokes of swimming safe, can I still do a normal yoga class if I avoided certain positions? Could I still work my abs?"

Her sister Kate had her third child, Prince Louis, earlier this spring.

With files from Lisa Yeung.

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