A few critics have slammed the actress for her role in the film, which also stars Salman Khan. One even criticised her for participating in the "shameless sexism" of Sultan as Aarfa sacrifices her Olympic medal dream to keep her child.
Anushka shared the letter on her Twitter account on Saturday.
The letter read that when Ms Azarenka was recovering from the knee injury that kept her out of Wimbledon, she and her boyfriend learned they were expecting a child at the end of the year.
"We couldn't be happier and feel very blessed to begin this exciting journey of building a family together," she wrote.
"I have been truly inspired by so many strong female athletes who return to the very top of their sport after having children," Ms Azarenka added.
"And I plan to do exactly that."
Anushka then tweeted:
Choosing motherhood over career is empowering. Choosing your career over motherhood is empowering. The Freedom to CHOOSE is empowering.? Anushka Sharma (@AnushkaSharma) July 16, 2016
Sultan, directed by Ali Abbas Zafar, also features Amit Sadh, Randeep Hooda, Kumud Mishra, Parikshat Sahni, Abhishek Duhan and Meiyang Chang. The film has so far garnered over Rs 300 crore worldwide.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)