"Its a BOY!!!!!!!!! :))))) We're thrilled!!!" Hebert tweeted Wednesday.
The seventh-season The Bachelorette couple apparently learned the sex of their child on Monday, when Rosenbaum jokingly tweeted, "Jockstraps or tampons, what's it gonna be? Less than an hour away!!"
Clearly, the result was jockstraps, which Rosenbaum ended up revealing to his followers on Twitter yesterday.
"I definitely saw J.P.'s profile on the ultrasound," Hebert, 30, told People of the baby, who's due in October. "I'm gonna be living with two J.P.s!"
"As excited as I am for this, I think I'm just as excited for my parents," Rosenbaum, 37, explained. "This is their first grandchild and [now] the Rosenbaum name lives on. Not to mention that my dad already called dibs on his first baseball mitt."
Hebert also told People why she didn't want to keep the baby's sex a surprise.
"I'm a planner, so finding out the baby's sex early definitely makes things easier on us when planning for the future. I've already started shopping for cute outfits!" Hebert said. "Now all I have to do is convince J.P. that he actually really loves the name I picked out."
Hebert will reportedly finish her dental residency in Philadelphia in June, and the pair revealed last month they'll soon be moving to Miami, FL.
Hebert and Rosenbaum announced the pregnancy news in late March and had said they're thrilled to be expanding their family. Hebert had told Life & Style around this same time last year she would like to have one child -- hopefully a girl -- while Rosenbaum had admitted he's gunning for two children and would love to have a boy.