Pregnant Rooney Mara dresses her baby bump in head-to-toe black as she steps out in LA on her 39th birthday while preparing for second child with Joaquin Phoenix

As Rooney Mara prepares for the birth of her second child with fiancé Joaquin Phoenix, the proud mother is also celebrating her birthday.

Stepping out on her 39th birthday in Los Angeles on Wednesday, the Academy Award nominee dressed her baby bump from head to toe in black.

She donned a cropped knit sweater over a matching singlet, which she tucked into stretchy pants with black Nike sneakers.

Mara revealed her pregnancy in February, when she debuted her baby bump on the red carpet of the premiere of her film La Cocina at the Berlinale International Film Festival.

The Women Talking actress draped her pregnant belly in a flowing black strapless dress.

When Rooney Mara stepped out on her 39th birthday in Los Angeles on Wednesday, she dressed her baby bump from head to toe in black

She donned a cropped knit sweater over a matching singlet, which she tucked into stretchy pants with black Nike sneakers

She donned a cropped knit sweater over a matching singlet, which she tucked into stretchy pants with black Nike sneakers

She and Phoenix, 49, welcomed their first child in August 2020, a baby boy named after Joaquin’s late brother River Phoenix.

Mara opened up about motherhood to People for her first Mother’s Day of 2021.

“As a new mother, Mother’s Day has taken on special meaning this year,” she said.

“Raising our baby, River, has opened my heart to a whole new life full of hope and more determination than ever to create a kinder and more sustainable world.”

The animal rights activist added: “I feel so lucky to be able to raise my son in all the ways nature intended, and I wish that all mothers in the animal kingdom could experience that sacred maternal bond with their young, without exploitation by people.’

She and Phoenix will soon be back on screen together after being cast in the upcoming films Polaris and The Island.

Written and directed by Lynne Ramsay, Polaris follows an ice photographer (Phoenix) who meets the devil in 1890s Alaska.

The married couple packaged filming on location last year in Alaska.

In The Island, the pair play a 1930s couple who move to a deserted island with the intention of living off the land.

Mara revealed her pregnancy in February, when she debuted her baby bump on the red carpet of the premiere of her film La Cocina at the Berlinale International Film Festival

Mara revealed her pregnancy in February, when she debuted her baby bump on the red carpet of the premiere of her film La Cocina at the Berlinale International Film Festival

She and fiancé Joaquin Phoenix welcomed their first child in August 2020, a son named after Joaquin's late brother River Phoenix.

She and fiancé Joaquin Phoenix welcomed their first child in August 2020, a son named after Joaquin’s late brother River Phoenix.

The couple will soon be back on screen together after being cast in the upcoming films Polaris and The Island

The couple will soon be back on screen together after being cast in the upcoming films Polaris and The Island

Production was stopped on the eve of filming in Spain last May, amid the upcoming Screen Actors Guild (SAG-AFTRA) strike.

After the SAG and Writers Guild of America (WGA) strikes concluded in the fall, the actors and Paweł Pawlikowski remain “committed” to this effort.

Mara said at the Berlinale that they “still have hope that we can make it,” tellingly Deadline: ‘We just don’t know when that will be.’

“It doesn’t look like that will happen this year,” Mara said. “But we are all committed to the project.”

Mara and Phoenix started dating in 2016 after starring together in 2013’s Her, and announced their engagement in 2019.

The couple also starred together in Don’t Worry, He Won’t Get Far on Foot and Mary Magdalene (both 2018).