Blake Lively gave birth to her first child with Ryan Reynolds in December in New York.
Sources told multiple news outlets about the birth, which took place sometime before the New Year near the couple's home in Bedford.
The baby, whose name and gender haven't yet been revealed, arrived earlier than expected, but both Lively, 27, and the child are doing well, sources said.
Lively and Reynolds announced the pregnancy -- a first for both -- in October.
The couple, who married in 2012, said they didn't want to find out the baby's gender before he or she was born.