While the make-up artist's dad Eric Holland recently insisted they are having a son, it has now been claimed the couple - whose little one is due in October - are having a daughter, according to a source closer to the pair.
A Kardashian insider told Us Weekly magazine: ''Rob couldn't be happier.''
The pair are said to be making preparations for an ''over-the-top extravagant nursery'' for their impending little one at the sock designer's $2.2 million Calabasas home.
Fans of the couple - who got engaged in April after four months of dating - will be pleased to know the cameras have already started filming Rob, 29, and Blac, 28, ahead of their E! series on her pregnancy.
A source said: ''Everything will be on the show.''
Rob is said to have grown closer to his mother Kris Jenner since finding out he is going to be a father for the first time.
The source added: ''Kris has been giving him baby advice. They get excited talking about the baby.''
What's more, Rob's sister Kim is said to be ''definitely the most involved'' out of his siblings, but Khloe - who has clashed with Blac in the past - is ''learning to accept'' the situation.
The former 'Kocktails with Khloe' host kicked Rob out of her home when she discovered he was dating Blac earlier this year.
Earlier this week, Blac's father claimed the pair told him they were having a son when they spent Independence Day with him on July 4.
He said: ''Rob and I have had some one-on-one time. All I can say is he's excited about the prospect of a boy.
''For Angie, the most important thing is that the baby is healthy. They were really excited when it kicked for the first time.
''They've chosen a name but they've not told anyone what it is. They want to wait until the baby is born.''
The actor says he isn't "holding out for more money or doing anything like that".
The drama will be making its return to the streaming service in the near future.
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