The 26-year-old jewellery and shoe designer has been very open in recent months about wanting to add to her brood, and even admitted that she hopes her next child is a baby girl.
She said earlier this year: "We know we want another one [baby] close in age to Camden and we're at the point where we're both ready. Before Camden was born, I thought I'd be pregnant again by the time he was six months, but I definitely wasn't ready. Now, I'm finally ready."
She added: "Obviously, I want a little girl, but if I had another boy I would be so excited as well. I love having a boy. Either way, I'd be really, really happy."
Kristin married Chicago Bears quarterback Jay, 30, in a low-key ceremony in Nashville, Tennessee, in June.