The couple is waiting till birth to find out the sex of the baby.
Speaking with Savannah Guthrie and Hoda Kotb on TODAY while promoting his upcoming holiday comedy movie with Will Ferrell and Octavia Spencer called Spirited, Reynolds told the two women that they always wait until the baby is born to find out the sex.
He also revealed whether or not he was hoping for a boy or girl, stating, "I know girls so I’m sort of kind of hoping that, but I’m ready for whatever happens."
But he had a bigger reason for not really wanting the baby to be a boy, based on personal experience: "(I come from) all brothers, which is why I speak from experience. I love my well-being and my home. I was the youngest of four and we were just arsonists and firemen."
Guthrie replied, "Now you’re the ultimate girl dad," and Reynolds agreed.
It's unclear when Reynolds and Lively's fourth baby is due, as the pair keep their private life, well, private.
Lively wrote, "Here are photos of me pregnant in real life so the 11 guys waiting outside my home for a 🦄 sighting will leave me alone. You freak me and my kids out."
"Thanks to everyone else for all the love and respect and for continuing to unfollow accounts and publications who share photos of children. You have all the power against them. And thank you to the media who have a 'No Kids Policy'. You all make all the difference 🙏♥️. Much love! Xxb," she continued.
Fans also speculated that the couple revealed the name of their unborn child in a Taylor Swift track, which would imply they already know the sex of their fourth child. In her Midnights track, "You're On Your Own, Kid," Swift mentions the name "Daisy Mae," which her fans immediately thought could be related to Reynolds and Lively's next little one, although it has not yet been confirmed.