<P> In baseball, the designated hitter rule is the common name for Major League Baseball Rule 5.11, adopted by the American League in 1973 . The rule allows teams to have one player, known as the designated hitter (abbreviated DH), to bat in place of the pitcher . Since 1973, most collegiate, amateur, and professional leagues have adopted the rule or some variant . MLB's National League and Nippon Professional Baseball's Central League are the most prominent professional leagues that do not use a designated hitter . </P> <P> In Major League Baseball, the designated hitter is a hitter who does not play a position, but instead fills in the batting order for the pitcher . The DH may only be used for the pitcher (and not any other position player), as stated in Rule 5.11 . Use of the DH is optional, but must be determined prior to the start of the game . If a team does not begin a game with a DH, the pitcher (or a pinch - hitter) must bat for the entire game . </P>

When did the dh rule start in baseball