Now, just seven months later, the actress said she's already noticed distinct differences between her baby and her oldest, 2-year-old Olive.
"I tap dance and I goofball for Olive all the time and she's a very serious customer," she said during an appearance on the "The View." "Frankie's the opposite. It's like everything is funny to her. It's wild! She's more like me. She's more goofy."
If it sounds like Barrymore, 39, is content with her life, that's because she is. She's even looking forward to her 40th birthday next year.
"Finally, finally I feel like a grownup and it feels so good," she said. "I've never been the age the way I felt, like it never matched, the numbers, and I'm like, 'No. I feel 40. This is great,' and I wouldn't go backwards for anything."
To learn more about her daughters, watch the video above.