Female tennis players who wish to freeze eggs or embryos, so they can start a family at a later date, will have their ranking protected by the WTA Tour.
The offer is open to any player ranked in the world's top 750 who spends more than 10 weeks out of competition.
The 2017 US Open champion Sloane Stephens says the rule will reduce the pressure on players to return to the court too quickly.
The 32-year-old, who has won eight WTA tournaments, told BBC Sport she has twice previously used the off-season to freeze her eggs.