Scarlett Johansson and fiancé Romain Dauriac have welcomed their first child.

In a statement to the AP, a rep for the couple confirmed that the Lucy actress gave birth to a baby girl - who they have named Rose - on Thursday (September 4).

[related]The spokesperson added that Scar-Jo and her newborn daughter are now resting comfortably.

The 29-year old was first rumoured to be expecting back in March, with Scarlett soon snapped sporting a visible baby bump.

Johansson - who was previously married to actor Ryan Reynolds - has been dating Dauriac since 2012, with their engagement confirmed last summer.

Congratulations!