The gender and name of Blake Lively and Ryan Reynolds' newborn child has reportedly been outed in a Twitter.com post by an excited hospital worker.

The Green Lantern co-stars became first-time parents just before the New Year (15), but the baby's sex, name and other details have yet to be revealed.

However, shortly after the birth news broke online on Monday evening (05Jan15), a woman who works at New York's Westchester Medical Center, not far from the couple's home in Bedford, sent a congratulatory tweet to the new parents and appeared to reveal the sought-after details about the celebrity offspring.

Sam, who tweets under the username @kimbanksy, wrote, "Congrats @blakelively #blakelively glad to have you and baby girl violet in our care".

A representative for Lively has yet to comment on the news of the baby's birth or name.

Lively and Reynolds wed in 2012.