"I'm just very grateful. I know it's such a privilege and a miracle," the Oscar-winning actor told Harper's Bazaar, where she revealed the news. "Tanguy and I are very excited."
Portman, 44, said her perspective on pregnancy has long been shaped by her upbringing as the daughter of a fertility doctor.
"I grew up hearing about how hard it is to get pregnant," she told the magazine. "I have so many people I love who have had such a hard time."
Portman said she has more energy than she expected, noting she is cherishing each moment because it will likely be her last pregnancy.
Portman shares two children - son Aleph and daughter Amalia - with her former husband, choreographer Benjamin Millepied.
The Black Swan and Thor star has many accolades, including an Academy Award, a BAFTA and two Golden Globe wins.
One of Portman's most anticipated upcoming films is the 2026 dark absurdist comedy The Gallerist, directed by Cathy Yan and starring Portman alongside Jenna Ortega, Sterling K Brown and Catherine Zeta-Jones.
The film follows a gallerist, played by Portman, who is driven by desperation and comes up with a scheme to sell a dead man at the renowned modern art show, Art Basel Miami.
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