Pippa Middleton is pregnant with her first child

Kate Middleton's sister, Pippa, has confirmed she is pregnant with her first child. (Reuters)

Pippa Middleton has confirmed she's pregnant with her first child!

The 34-year-old mom-to-be wrote a guest column for U.K. supermarket monthly, Waitrose Kitchen magazine, where she opened up about her pregnancy and how things are going in her first trimester.

“I was lucky to pass the 12-week scan without suffering from morning sickness. That meant I was able to carry on as normal,” Middleton wrote, per Hello! Magazine, adding that she kept her pregnancy a secret until the "riskier months" were over.

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“When I learned the happy news that I was pregnant I realized I needed to adjust my four to five-day-a-week routine,” she explained.

In April, reports arose that Middleton was expecting her first child with husband James Matthews. The couple had yet to confirm the news, yet made an appearance later in the month to attend Prince Harry and Meghan Markle's wedding.

Since learning she was pregnant, Middleton says she has been trying to figure out the best way to safely continue working out.

“I’m fanatical about sport and have looked at loads of books and websites on exercise during pregnancy but have been disappointed by the limited technical information on what you can and can’t do,” she wrote. “And this being my first pregnancy, I had so many questions I felt were still unanswered.”

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“So I decided to use my own initiative and adapted my current exercise routine, adjusting the weight and intensity to what felt right for me,” Middleton continued. “I work out for 45 minutes, three to four times a week depending on my energy levels, but ensured that the routines I did were lighter than usual."

“I’ve noticed my body change and weight increase, but through effective exercise and sports I feel that it’s been strengthened to support a healthy pregnancy, birth and recovery," she added. "And ensure that post-baby, my old favorite jeans will still fit eventually!"

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Meanwhile, Pippa's sister, Kate, recently gave birth to her third child, a son named Louis. The newborn was absent at Meghan and Harry's wedding, but Kate arrived with Prince George and Princess Charlotte.