Jessica St. Clair and husband Dan O'Brien welcomed a health baby girl into the world in Santa Monica, Calif. on Tuesday, Oct. 1. Credit: Jason LaVeris/FilmMagic

And baby makes three! Jessica St. Clair and husband Dan O'Brien welcomed a health baby girl into the world in Santa Monica, Calif. on Tuesday, Oct. 1, a rep for the Best Friends Forever actress confirms to Us Weekly.

The couple wasted no time finding a fitting name for their daughter either: Isobel Kelly O'Brien. Their tiny bundle of joy weighed in at 9 lbs., 9 oz., according to the rep.

The 36-year-old actress, who has also had smaller roles on 2012's Wanderlust and 2011's Bridesmaids, as well as a guest spot on the last season of The Office, will next rejoin pal Lennon Parham on new USA sitcom Playing House.

The close friends previously costarred on short-lived TV series Best Friends Forever, and have been sharing several watershed moments in the past year.

Parham gave birth to daughter Saraya in April, and the pair even got married within a week of one another in July 2006.