Kim Kardashian West and Kanye West are expecting a girl.

The couple will welcome a third child via a surrogate in January 2018 and insiders have revealed that the new addition to their family will be a daughter.

A source told PEOPLE: "They are so excited about their future baby girl. They can't wait to add a new addition to their family and are just so incredibly happy."

And Kim and Kanye - who have children North, four and Saint, 21 months, together - have been extremely involved in the pregnancy so far.

An insider said: "Kim and Kanye have been incredibly involved in the surrogate process. Kim has been super adamant that the surrogate sticks 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."

While Kim, 36 and Kanye, 40, are excited to add to their family, North is not so thrilled.

The source said: "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 thinks it's just a phase and are hoping she will grow out of it."

Kim has previously spoken about North's jealousy of Saint, explaining: "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. She would get so jealous when I would breastfeed and all that kind of stuff. And now, the phase isn't going away."