Is Princess Charlotte set to become a big sister before she even turns one?!

According to a new report, Kate Middleton is pregnant with her and Prince William's third child just four months after welcoming their daughter.

kate middleton

Kate Middleton with Princess Charlotte in May.

“She’s in the early stages of pregnancy with baby No. three,” a source tells Star magazine, adding that the addition is due "in late April or early May, so she’ll likely be showing by the New Year."

This could explain why the 33-year-old has been a no-show at several important events, including the wedding of her friend Daisy Dickson last month.

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"Kate has the Queen's blessing to forgo royal duties for at least two months, until she overcomes the treat of sickness," the insider explains. “She’s not taking any chances.”

kate middleton

Kate while pregnant with Charlotte.

The brunette beauty is also said to be planning her vacations around her growing belly. "She knows the paparazzi will try everything to get the first photos of her bulging swimsuit — that’s why she wanted to take an earlier vacation," the source says.

"She figures her bump won’t be prominent in November, so she can relax in her bikini without her pregnancy being so obvious.”