"Thank you for all the love!! We are so excited for Camden to be a big brother!" she wrote.
Cavallari, who married Cutler in June, has been open about her desire to expand her family.
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"We want to have a second sooner rather than later," Cavallari told E! News last month. "We know we want another one close in age to Camden and we're at the point where we're both ready."
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Initially, the former reality TV star thought that she'd start trying for a second child six months after giving birth to Camden, but she "wasn't ready." Now, she's hoping that her second child is a girl.
"Obviously, I want a little girl, but if I had another boy I would be so excited as well," she said. "I love having a boy. Either way, I'd be really, really happy."
