Birth control has been practiced since the dawn of history.
For instance, contraceptive pessaries (vaginal inserts) that used a spermicide, acacia gum, were common in Ancient Egypt. And in 12th century India a potion made of powdered palm leaf and red chalk, as well as vaginal suppositories containing honey, ghee, rock salt and the seeds of the palasa tree, were used, all with varying degrees of effectiveness.
More recently, Margaret Sanger opened the first birth control clinic in the United States in 1916 and introduced the diaphragm to women, letting them finally take control of their fertility. Family size shrank from 7 to 2.3 children in the first 3 decades of the 20th century.
Since then there has been a revolution in birth control and most methods are now—if used as recommended—pretty fail-proof.