Conversation so far:
When was Martina Hingis's first retirement from tennis?
In February 2003, at the age of 22, Hingis announced her retirement from tennis.
How long did Martina Hingis stay in her first retirement?
Martina Hingis was retired for approximately 2-3 years.

Question: Why did she decide to retire?
Self-contained rewrite: Why did Martina Hingis decide to retire in 2001?