Girls run the world in the Bell-Shepard household.

Kristen Bell and Dax Shepard welcomed their second child on Dec. 19, a baby girl named Delta Bell Shepard. The newborn joins her big sister, one-year-old Lincoln.

"Delta Bell Shepard is here. She doesn't look like either @IMKristenBell or me, but we're gonna keep her anyway. #christmascameearly," Shepherd tweeted.

Bell joked about her husband becoming outnumbered in the family full of girls. The couple welcomed their first child in March 2013 and married in October 2013 following the Supreme Court's decision to recognize gay marriage.

"The estrogen has now hit critical mass! Good luck, @daxshepard1. And welcome to the world DELTA BELL SHEPARD :)," she tweeted along with a photo of a gorilla hand entwined with its child's fingers.

The "Frozen" star put her second pregnancy on full display in a commercial for the Samsung Galaxy Tab S and the holiday-themed ad for Samsung Mobile also co-starring her husband.

Bell stars in the fourth season of Showtime's "House of Lies" starting on Jan. 11. Shepard will wrap up "Parenthood" after six seasons early next year.