Barron is "doing great" and asking a lot of questions about the campaign, Melania Trump said.
"Of course, he misses his dad a lot these days. But he's doing great," she added.
She also previewed one of the causes that she hopes to focus on if she becomes first lady.
"I will focus on helping children and women, and also about social media. In this 21st century, what's going on, it's very hurtful to children. To some adults as well, but we need to take care of children," she said.
Trump said children get hurt "by social media" and "we need to teach them how to use it, what is right to say, what is not right to say … because it's very bad out there."
She said she gives her husband advice on tweets "all the time," and while Donald Trump has been known to verbally attack his opponents on Twitter, he acknowledges that his wife’s concern about the negative effect of social media is "true."
"I've seen so many people hurt so badly,” Donald Trump said. “Not just children, I mean, just people are hurt so badly by new social media. And she feels very strongly about it. She understands it very well.”