Former American Idol judge Kara DioGuardi is a new mother after welcoming her first child via surrogate.

The songwriter and her husband Mike MCCuddy are now the proud parents of little Greyson James Carroll MCCuddy.

A gestational surrogate gave birth to the baby boy in Los Angeles on Thursday (31Jan13), DioGuardi tells People.com.

The 42-year-old star gave her son the middle name Carroll in honour of her late mother.

DioGuardi turned to a surrogate following a series of fertility issues and failed in vitro fertilisation (Ivf) attempts, and she recently praised the unidentified woman, insisting, "She's given us an incredible gift."