General view of the netting above the Los Angeles Dodgers dugout during the game against the St. Louis Cardinals in the ninth inning at Dodger Stadium on August 7, 2019 in Los Angeles.

All 30 Major League Baseball teams will expand the protective netting in stadiums starting with the 2020 season, baseball Commissioner Rob Manfred told CNBC in an interview Wednesday.

The protective netting will extend "substantially beyond the end of the dugout," Manfred told CNBC at the league's winter meetings in San Diego.

The change comes after a 2-year-old girl who was hit by a foul ball at Minute Maid park in Houston was hospitalized in May. She suffered a fractured skull, seizure, subdural bleeding, brain contusions and brain edema, doctors said at the time. Another 2-year-old girl was struck in the face by a 105-mph line drive at Yankees Stadium in 2017.

Manfred said earlier this year the league wouldn't likely make changes to the protective netting during the 2019 season. Those changes are, however, coming next year, he said in an interview.

Manfred said seven or eight clubs will extend the netting all the way to the foul poles, with another 15 teams extending it "down to the elbow" areas of playing fields.

"The reason for that is when the stadiums jut away you have to run cables over the playing field to go all the way to the foul pole, so it's very difficult structurally to do," Manfred said. "And then we had a group of clubs who were already well beyond the dugout, and they are going to continue in that mode."

Technically, there is no rule forcing teams to extend the netting, but after the league office met with each club, both parties decided to make the move.

"There was no rule passed or anything like that," Manfred said. "We just went out, talked to the clubs, made the case that extending netting was the thing to do, and the clubs individually responded in a positive way."

An NBC News investigation found that from 2012 to 2019, there were at least 808 reports of injuries to fans from baseballs, the national news network reported in October. These injuries ranged from concussions to permanent vision loss.

While most of the injuries were caused by foul balls, other injuries resulted from home runs and batting practice, NBC found.