Loeb, 41, and husband Roey Hershkovitz welcomed Lyla Rose Loeb Hershkovitz Sunday morning at Los Angeles' Cedars Sinai Medical Center, according to the magazine.
Lyla is the first child for the "Stay (I Missed You)" singer and her husband, 31, a music production supervisor on The Tonight Show with Conan O'Brien. The couple married in January 2009.
Aside from her chart-topping songs such as "Stay" and "I Do," Loeb starred in her own E! reality series #1 Single, documenting her search for love in her mid-thirties.