The actress said that the industry is so competitive that she worries she would be replaced by younger stars if she were to take some time out.
She told GQ: "If I wanted to have a family now, would I be able to come back to work in a couple of years?"
Ryder, whose latest role in Black Swan sees her prima ballerina Beth replaced by younger dancer Nina, admitted that it is not unusual for this to happen in Hollywood.
The 39-year-old explained: "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."
Ryder also confessed that she is inspired by Meryl Streep, who is still making movies at 61.
She added: "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."