"I wasn't sure I was going to make this public," Shields tells People. "I'm thrilled for my daughter to have a little friend. Two Tauruses, it's a huge trick being played on me."

Shields' current daughter Rowan, was the subject of the Suddenly Susan star's book Down Came the Rain: My Journey Through Postpartum Depression.

The book gained notoriety when her former pal Tom Cruise criticized the subject matter as irresponsible because of his religion, Scientology, which teaches that psychiatry is a "pseudo science" and all drugs are dangerous. Cruise is expecting a child of his own with fiancee Katie Holmes.

This pregnancy is especially gratifying since Shields didn't have to go through the process of in vitro fertilization, which she and her husband, TV writer-producer Chris Henchy, used to conceive her first child.

Shields, 40, is best known for her early film work in Pretty Baby, The Blue Lagoon, Endless Love and Brenda Starr. On television she starred in the sitcom Suddenly Susan and had a recurring guest role on "The '70s Show" playing the mother to Mila Kunis' character. In October, she left her starring role as Roxie Hart in the revival of the musical Chicago.