Boston Cardinal Sean O'Malley is calling on Catholics to participate in nine days of "prayer, penance and pilgrimage" to mark the 40th anniversary of the U.S. Supreme Court decision that legalized abortion.

O'Malley is the chair of U.S. bishops' Committee on Pro-Life Activities.

O'Malley called on Catholics to begin the nine days of prayer and penance on Saturday. The Supreme Court handed down its decision in Roe v. Wade on Jan. 22, 1973.

O'Malley said there's been a staggering loss since the ruling, as tens of millions of children "never had the chance to be born." He criticized the court and abortion supporters for reducing that loss to a matter of personal choice.

In a statement, O'Malley said the "evil of abortion inflicts unimaginable pain," but he said Jesus offers renewal.