Why Kim and Kanye Were 'Thrilled' to Expect a Daughter — and 'Adamant' About Surrogate's Diet

Another Kardashian girl has made her debut — and her parents couldn’t have been happier about her impending arrival.

A source told PEOPLE in September that Kim Kardashian West and husband Kanye West were “thrilled” to be expecting a daughter, sharing, “They are so excited about their future baby girl.”

Earlier that week, multiple sources confirmed to PEOPLE that the couple’s surrogate was pregnant with their third child. They are also parents to son Saint, 2, and daughter North, 4½.

“They can’t wait to add a new addition to their family and are just so incredibly happy,” the first source said, adding that the baby was expected to arrive in January.

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Back in June, PEOPLE learned that the couple had hired a surrogate to help them expand their family. The news came some time after Kardashian West was advised of the risks of carrying another child on her own due to her struggles with placenta accreta during both her previous pregnancies.

“Kim and Kanye have been incredibly involved in the surrogate process,” the September source said, noting that Kardashian West, 37, had been “super adamant” in ensuring the surrogate stuck to a healthy diet.

“Kim and Kanye both want the healthiest baby possible and are making sure the surrogate is abiding by the routine they’ve set for her,” added the source.

But not everyone was quite as excited about the family’s incoming fifth member. Explained the source, “North isn’t the most thrilled to be a big sister again.”

“She’s had the tendency to get really jealous about Saint and wants all of the attention to herself, but Kim and Kanye think it’s just a phase and are hoping she will grow out of it,” the source added.

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Kardashian West herself opened up about North’s sibling rivalry with Saint in August, while guest hosting Live with Kelly & Ryan.

“I don’t know if it’s because she’s the older sister. I don’t know what it is. I thought it was a phase. She does not like her brother and it’s so hard for me,” said the reality TV star.

Explained Kardashian West, “She would get so jealous when I would breastfeed and all that kind of stuff. And now, the phase isn’t going away.”