Kate's brother James Middleton hints he's going to be a dad with cryptic photo

James Middleton has caused a frenzy among his social media follows after hinting his wife could be pregnant.

The 34-year-old, who is the brother of the Duchess of Cambridge, sparked rumours he's going to be a father after sharing a post to celebrate Mother's Day.

Writing on Instagram on Sunday, which was Mother's Day in the UK, James said: "Happy Mother's Day to all the mother's (especially my mother), grandmother's, dog mum's and soon to be mother's out there".

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The "soon to be" mothers comment had fans speculating he was referring to wife Alizée Thevenet.

The post didn't include any photos of James or Alizée, instead featuring a group shot of the couple's four dogs.

But fans immediately commented, asking him to confirm the news.

"Ahhhhhh is someone having a baby?" one asked.

"Soon to be meaning Alizée?" another said, with another adding, "That's how I interpreted that's too..."

"Is Alize pregnant?" asked another.

"Omg are you guys having a baby?"

While one asked James to clarify if he meant his sister.

"KATE OU [or] ALIZEE?"

Another follower replied to that comment with, "Not Catherine because she had a sip of alcohol on the tour".

So far neither James nor Alizée have confirmed the news.

If Alizée is expecting, the child would be the third niece or nephew for Kate, who is aunty to Pippa's two children, Arthur and Grace.

James and Alizée married in September last year in the small hilltop town of Bormes-les-Mimosas in the south of France. The bride revealed her wedding dress had a very special backstory.

"My 'something borrowed' was in fact my dress from my mother-in-law Carole, who last wore it 41 years ago on her wedding day in June, 1980," Alizée told Hello.

"It fitted me perfectly and was exactly what I wanted."

The town's mayor François Arizzi officiated the civil union inside the town hall.

He told local publication Var Matin the wedding was small and intimate and attended by just 50 guests, including the Duke and Duchess of Cambridge, Carole and Michael Middleton and Pippa and James Matthews.

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"Prince William and Kate were there but they did not want to steal the show from the newlyweds, Alizée Thevenet and James Middleton, who is a very nice boy," Arizzi told the publication.

He said William was dressed casually in a "beige and off-white suit".

The duchess, he said, was dressed in a "long dress of a very light green colour"

James shared the happy news on Instagram soon after, including a photo of him and his bride — and one of their dogs.

"Mr and Mrs Middleton," he wrote.

"Yesterday I married the love of my life surrounded by family, friends and of course a few dogs in the beautiful village or Bormes-les-Mimosas. Words cannot describe how happy I am."

The couple became engaged in October of 2019, but was forced to postpone their nuptials twice due to the coronavirus pandemic.