The decision was made at FI's autumn meeting in Switzerland last week.
It was also decided there that the prize money will be increased by 10 percent for this season.
The additional money must be distributed to the first 20 in the overall cup on both the men's and women's side.
As for the sprint relays, now instead of two semi-finals, the two team members of each two-man team will run individual prologues.
Their times are added up and the 15 teams with the best overall time will get to run the sprint relay.
Earlier during the WC, 10 teams participated in the final.
Now it will be an even tighter competition with 15 teams on the starting line.