For Joanna Gaines, expecting baby No. 5 should’ve felt totally routine. It didn’t. Eight years after her last pregnancy, "I have forgotten almost everything," said the mom of Drake, 13, Ella, 11, Duke, 9, and Emmie, 8. "So it feels brand-new."

The same goes for giving birth. In the days leading up to the summer arrival of her third son with husband Chip, Life & Style has learned the Fixer Upper star, 40, was plagued by drama and anxiety over everything from the couple’s busy workload to logistical concerns about the delivery. "She’d been excited about finally holding her baby boy, but at the same time she was incredibly nervous," says a source. "The baby had been very active, which made Joanna think that he might arrive early. It would be a nightmare to be home alone with the kids if she went into labor unexpectedly."

But that scenario was a very real possibility. Their hit HGTV show went off the air in April after five seasons ("We gave everything we had to [Fixer Upper]… but this just felt like the right time to catch our breath," says Jo), but her husband and co-star, Chip, 43, was still busy holding down the couple’s many Waco, TX, businesses during her final weeks of pregnancy. "Chip is often out and about," reveals the source. "Joanna was worried that he wouldn’t be around if she went into labor early."

She knew that if that happened, she’d have to get herself to the hospital — and also to quickly figure out who would watch her four kids. And there were other kinds of concerns for Joanna, who wondered how the brood would react when she brought their new brother home, says the source. Though Jo has said the children were excitedly touching her bump each day during the pregnancy, she feared the excitement could wane once he was born, the source explains, if "jealousy issues" arose.

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Cuddle bug 😍

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Juggling four older kids with a newborn is tough on any mom. And Joanna — who admits she needed a refresher on diaper changing before welcoming the baby — knows that. "She’s hands-on," says the source, "and obviously realizes how much hard work goes into raising kids." Still, she’s counting on her brood to rise to the occasion. "We’re all rallying around this baby," says the talented multitasker. Chip’s special assignment? Swaddling. "Chip is the best swaddler," says Joanna. "He’s always been able to rock our babies to sleep. He’s like, 'I’m going to be holding the baby the entire time!'"

And if things go well with everyone, there could be yet another sibling on the way soon enough! "I’m open to whatever," Joanna says of baby No. 6. "I’m just having fun with it."