During an appearance on The Late Show with Stephen Colbert Thursday, she told the late-night host that she welcomed her second child, a baby boy named Spencer, last month.

“I’m telling it for the first time now, it feels so strange. But I gave birth to a baby boy on September 3.”

“No one even knew you were pregnant!” Colbert said.

“I know! I know! This is news to a lot of people,” the actress said. “It’s true.”