Former Heroes star Hayden, 26, welcomed daughter Kaya in December with boxer fiancé Wladimir Klitschko.
Her rep said in a statement: "Hayden Panettiere is voluntarily seeking professional help at a treatment centre as she is currently battling postpartum depression. She asks that the media respect her privacy during this time."
Just last month, 26-year-old Hayden opened up on Live! With Kelly and Michael about her post-baby struggles and whether she can relate to her Nashville character Juliette Barnes, who also suffers with it.
"It's something a lot of women experience. When [you're told] about postpartum depression you think it's, 'I feel negative feelings towards my child, I want to injure my child or I want to hurt my child.' I've never, ever had those feelings. Some women do.
"But you don't realise how broad of a spectrum you can really experience that on, and it's something that needs to be talked about. Women need to know that they're not alone, and that it does heal."
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