Kate Middleton's sister Pippa is finally pregnant.

Another baby is on the way for the Middletons. According to Clemmie Moodie of The Sun on Sunday, Pippa is expecting her first bundle of joy with husband James Matthews.

The Duchess of Cambridge was reportedly delighted after learning that her sister is expecting too. She was the second person that Pippa told about the news after her husband.

"When Pippa found out she was pregnant, she was obviously thrilled and utterly overjoyed," a family friend said. "Naturally, big sister Kate and parents, Carole and Michael, were the first people she told — James aside — and they could not have been more delighted."

In 2017, a source revealed that Kate and Pippa have always wanted to get pregnant simultaneously. However, while they are now both expecting, Kate is due to deliver her baby soon while Pippa's child is arriving in October.

"It's long been a dream for Kate and Pippa to be pregnant at the same time," a Middleton family friend revealed. "To share that would be amazing."

Pippa's upcoming baby provided "some much-needed happiness and light relief" to her family. In March, her father-in-law, David Matthews, was arrested at Paris Orly airport and was chaged with sexual assault. David denied the accusations.

"David Matthews categorically denies the allegation and unequivocally contests the untrue and scandalous accusation," the family spokesperson said.

David allegedly attacked a teenage girl between 1998 and 1999 in Paris and St. Barts. He was placed in custody at the Brigade for the Protection of minors and spent 48 hours there. The French authorities is investigating him and they have six months to decide if they will bring him to trial.

Pippa married James in May 2017. Prince George and Princess Charlotte served as her page boy and bridesmaid on her wedding. The two little royals are expected to have the same role for Prince William and Meghan Markle's royal wedding.

On the said event, Kate was reportedly worried about her children's behavior. She feared that the two would misbehave.

"[Kate] said that they were all really looking forward to her sister's wedding at the weekend, but she was a bit worried about how her children might behave," Andrew Bates told People. "She said she was hopeful that they would be good, but you never know at that age."

Pippa Middleton Kate Middleton's sister Pippa is expecting her first baby. Pictured: Pippa and Kate sit in the Royal Box during the Gentlemen's Singles final match between Roger Federer of Switzerland and Andy Murray of Great Britain on day thirteen of the Wimbledon Lawn Tennis Championships at the All England Lawn Tennis and Croquet Club on July 8, 2012 in London. Photo: Getty Images/Clive Brunskill