Ali Larter has given birth.

The 38-year-old actress has welcomed her second child into the world, Vivienne Margaret MacArthur, with husband Hayes MacArthur, and she admitted the couple - who already have four-year-old son Theodore - ''couldn't be more excited'' about their new arrival.

She wrote on her website: ''It's a girl! We couldn't be more excited to share news of the arrival of Vivienne Margaret MacArthur on Thursday January 15th 2015. She came bearing gifts for her brother: Batman sheets and lots of Gummy Bears!!! 7.5 lbs of love. (sic)''

The former 'Heroes' actress - who played the dual roles of Niki Sanders and Tracy Strauss in the sci-fi series - previously admitted she was craving lobster rolls and onion rings during her second pregnancy.

She said: ''I can't deny myself. I convince myself the baby is desperate for that lobster roll or those onion rings. I'm in the northwest right now so it's all about fried clams and lobster rolls.''

But, unlike when she was expecting Theodore, the couple decided not to find out whether they were expecting a boy or a girl this time around.

She said: ''I don't think we're going to [find out]''.

''Last time, we knew we were having a boy but this time, it's fun having this little surprise in here.''

During her first pregnancy, Ali announced on an episode of 'Late Night with Jimmy Fallon' in September 2010 that she was expecting a boy.