"We are beyond excited to meet our baby girl!" De La Garza and her husband, writer Michael Roberts, told the magazine in a statement.
De La Garza, 36, most recently starred on the NBC drama Do No Harm, which was canceled earlier this week after just two episodes.
"To all my peeps...Thank you for your warm wishes about #DoNoHarm," she tweeted on Saturday. "Alas, this is the way things go sometimes. Onward to our new adventures!"
The couple is already parents to 2-year-old son Kieran.