Rooney Mara talks raising son with Joaquin Phoenix: 'I feel so fortunate'

Rooney Mara is opening up about raising her son, River, whom she shares with Joaquin Phoenix.

As part of Farm Sanctuary's Mother's Day campaign, the "Carol" actress penned a heartfelt letter ahead of celebrating her first Mother's Day.

"As a new mom, Mother's Day has taken on a special meaning this year. Raising our baby, River, has opened my heart to a whole new life filled with hope and more determination than ever to create a kinder and more sustainable world," she wrote.

Rooney, who welcomed her baby boy last year, also shared how lucky she feels to be able to care for her son, named after Phoenix's 's older brother who died in 1993.

"I feel so fortunate to be able to nurture my son in all of the ways that nature intended," the "Girl with the Dragon Tattoo" star said, "and I wish all mothers in the animal kingdom could experience that sacred maternal bond with their young, devoid of exploitation by humans."