The `Girl, Interrupted` star has no plans to start a family in the near future in case motherhood ruins her chances of appearing in more films.
She said: "If I wanted to have a family now, would I be able to come back to work in a couple of years?"
The 39-year-old actress` reluctance to get pregnant may be due to Hollywood`s attitude towards ageing actresses, and her latest role in `Black Swan` - in which she portrays prima ballerina Beth MacIntyre who is being replaced by younger dancer Nina, played by Natalie Portman, in a production of `Swan Lake` - has done nothing to ease her fears.
Winona said: "I thought it was a cool parallel. Being replaced by the young thing. I know that definitely happens in Hollywood. It`s harder to find good roles, and suddenly there are new girls.
"I`m at that age I`ve been warned my whole life about."
Winona looks to 61-year-old Oscar winner Meryl Streep for inspiration when it comes to balancing her work and personal commitments as she approaches 40.
She told the US edition of GQ magazine: "It`s hard to imagine a time where Meryl Streep wasn`t the first choice for everything, but I was reading some article, and she said something like, `Yeah, when I was around 38, 39, I turned to my husband and said, `Should we just call it a day, or should we try to kick the can down the road?`
"It was so weird to me to think about movies without her in them. But a lot of great actresses have chosen that."