And with "Mad Men" making its return next week after a 17-month hiatus, there was no maternity leave for this new mom, who has since kept mum on who Xander's dad is.
"I was back when the baby was only 6 or 7 weeks old, so it was difficult," the actress, 34, told Us Weekly about her return to the set at the "Mad Men" Season 5 premiere in Hollywood on Wednesday. "It was difficult to be a working mom and just juggling all of that. But everyone made it work, and it was great."
But luckily for both Jones and her son, 7 months, the team at "Mad Men" was more than willing to make things work for the first-time mom.
"They made it baby-friendly for me, because I'm the first female on set to have a baby so I got to bring him," she said. "He had his own room and I was able to work around it because I was nursing."
Off-set, Jones is over the moon over her little man.
"He is eating solids and he is just jabbering away. He's becoming more of a little person. He is quite a charmer!" she explained of his milestones. "I love to make him laugh. He thinks I'm funny and that's always a nice feeling."
Adds the star's "Mad Men" castmate Jon Hamm about the little one, "He is a lovely lad and he is as cute as a button!"
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