They shared the news in a joint Instagram post, featuring a black and white video, set to The Beatles tune Here Comes The Sun.

Hugging and kissing in the short clip, they are joined by their first daughter, Ottilie Rue Deyes, who will be two years old in August.

They all look at ultrasound scans of the new baby, before Ottilie kisses her mother's tummy.

Both Sugg and Deyes added the message: "Our family is growing! Little girl joining us in December".

The couple, who live in Brighton, have been together since 2012. They have been dubbed Zalfie - a portmanteau of their two names.

In a video uploaded to her YouTube channel on Monday, she said: "You have noticed, I haven't been uploading on this channel as regularly as I used to do, there's a reason for that.

"We're having another baby."

She added: "I do really, really appreciate the people that have asked how I am.

"That's been very, very sweet to read, especially in moments where it just feels like there's a lot of pressure - like I want to film but I don't feel like I can and I'm not feeling great.

"It was really reassuring to me to know that like so many of you were just hoping I was okay."

Sugg said she had known "from day one" that the child would be a girl.

"I just knew. It was like every vision I had, was Otti and a little sister," she said.

"I imagine Alfie with two little girls (and) I said before we found out, 'I would be so shocked if this was a boy' because I am so sure."

She said there were "differences and similarities" between her pregnancies, but that she was now "starting to feel more like Zoe" again.

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"Honestly, we are beyond grateful beyond lucky beyond excited to have another little girl," she said.

Sugg - who is the older sister of fellow YouTuber and Strictly Come Dancing star Joe Sugg - began her career as a fashion, beauty and lifestyle influencer in 2009, and now has over 10 million subscribers.

She previously shut down rumours that she and Deyes were engaged, which began after she was pictured in 2021 with what appeared to be a gold diamond ring on her engagement finger.