(Cover) - EN Showbiz - Sienna Miller admits that her mind malfunctions when her daughter starts "screaming upstairs."

The 30-year-old actress gave birth to her first child Marlowe with beau Tom Sturridge less than a month ago.

Sienna is in awe of how adorable her newborn is.

"She's so cute," she gushed over the telephone at HBO's Summer Television Critics Association panel in Beverly Hills this week.

"She's screaming upstairs. My brain doesn't work."

Sienna was unable to attend the event with her The Girl director Julian Jarrold and co-stars Toby Jones and Penelope Wilton.

The star is simply overwhelmed with maternal obligations at the moment.

HBO film The Girl is out later this year. Sienna plays Tippi Hedren in the movie, which chronicles Alfred Hitchcock's obsession with Tippi after he directed her in movies The Birds and Marnie. Sienna called her work on the film "intense", "challenging" and "a lot of fun". (C) Cover Media