The 39-year-old TV personality and wife Nancy Juvonen welcomed their first child, a daughter Winnie last year, via surrogacy, reported Contactmusic.
"You have a baby, which you've been wanting for a long time. You felt very lucky that it happened at all. We had a long struggle with that. We did," Fallon said.
"There'll be nights when you're sitting on your couch, and you're with your beautiful wife, who you can't believe married you, and your beautiful baby, who you feel endlessly grateful you were able to have," he added.