"We were always planning on having three kids," Lowe told Us Weekly. "This one came maybe a little sooner than we had planned, but we are excited. The idea of raising three kids under three and a half years old, that's a little daunting if I'm being honest!"
The former reality star added that he was "genuinely excited" when he found out his wife was pregnant, though he joked that she Lowe may have not felt the same way.
"Her first thought was probably not excitement!" Lowe said. "Her first thought was probably, 'Wait, we're having a baby? I already have a baby! I'm not ready for another baby!' But after a few hours I think she got excited."
The couple's upcoming arrival will join big brothers Samuel, 3, and Isaiah, 1, the former of whom is clearly excited to welcome his new sibling.
"Samuel is constantly kissing mommy's belly and telling the baby he loves him or her," Lowe shared. "We always like to ask him, 'What do you think it's going to be?' And he says girl more often than boy."
Samuel's mom likely shares the same sentiment, as Giudici Lowe previously telling PEOPLE that she's "praying for a girl."
"I had wanted to try for a girl and so that went through my head," she said. "That went out the window! I thought, 'Oh my gosh, I might have a third boy!' And we won't find out until it's born. We've done that every time."
"I definitely am praying very hard for a girl. I'm trying to think girl thoughts," she joked, adding that ultimately, it doesn't matter whether she has a son or daughter.
"That's why we don't want to find out. I'm going to love this baby no matter what," the 33-year-old explained. "I'm going to find out when I meet it and love that baby."
Lowe and Giudici Lowe met on Lowe's season of The Bachelor, where Lowe chose his future wife as the season's winner. The two tied the knot in a televised wedding special in January 2014.
The couple has been open about the fact that they want a big family, with Giudici Lowe telling Us Weekly in May that she originally wanted five children.
"Originally when I met Sean, I wanted five [kids]," she said. "[Lowe]'s like, 'Whoa.' I'm like, 'OK, maybe four.' … I want a girl naturally next and then [to] adopt a girl. Then you get sisters and brothers. I know it's probably not going to happen, but that's my ideal."
Photo Credit: Instagram / @catherinegiudici