Accepting this as true for the sake of argument, one of the mechanisms by which birth-control pills work is by preventing implantation of a fertilized egg in the uterine lining.
This is also the primary means by which IUDs work.
If one takes the position that "Life begins at conception", then far more than 800 girls lose their lives every day due to their mother's birth-control practices.
And far more than 54 million babies have lost their lives since 1973