Thousands rally on the National Mall for the start of the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

A pro-life demonstrator holds a cross during the Ninth Annual Walk for Life West Coast rally in San Francisco, California, January 26, 2013. Thousands of pro-life demonstrators marched in San Francisco to mark the 40th anniversary of the Roe v. Wade U.S. Supreme Court decision legalizing abortion. REUTERS/Stephen Lam (UNITED STATES)A - Tags: ANNIVERSARY CIVIL UNREST POLITICS HEALTH RELIGION) 

A group of pro-life demonstrators hold signs as they march on Market Street during the Ninth Annual Walk for Life West Coast rally in San Francisco, California, January 26, 2013. Thousands of pro-life demonstrators marched in San Francisco to mark the 40th anniversary of the Roe v. Wade U.S. Supreme Court decision legalizing abortion. REUTERS/Stephen Lam (UNITED STATES - Tags: ANNIVERSARY HEALTH POLITICS CIVIL UNREST) 

Pro-life demonstrators hold a banner as they prepare to march during the Ninth Annual Walk for Life West Coast rally in San Francisco, California, January 26, 2013. Thousands of pro-life demonstrators marched in San Francisco to mark the 40th anniversary of Roe v. Wade U.S. Supreme Court decision legalizing abortion. REUTERS/Stephen Lam (UNITED STATES - Tags: ANNIVERSARY HEALTH POLITICS CIVIL UNREST) 

A group of clergymen stand outside City Hall during the Ninth Annual Walk for Life West Coast rally in San Francisco, California, January 26, 2013. Thousands of pro-life demonstrators marched in San Francisco to mark the 40th anniversary of Roe v. Wade U.S. Supreme Court decision legalizing abortion. REUTERS/Stephen Lam (UNITED STATES - Tags: ANNIVERSARY CIVIL UNREST POLITICS HEALTH RELIGION) 

Paisley Fowles, aged one, of Naples, Florida, sleeps on her father's shoulder amidst the din of the annual March for Life rally at the U.S. Supreme Court building in Washington, January 25, 2013. The anti-abortion marchers marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst 

Signs are seen in the snow at the start of the annual March for Life rally in Washington, January 25, 2013. Anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

People participate in the annual March for Life rally on the National Mall in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS HEALTH CIVIL UNREST) 

Participants rally on the National Mall for the start of the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

Activists hold signs reading "I regret my abortion" on stage as they participate in the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

Thousands rally on the National Mall for the start of the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

Participants in the annual March for Life rally pass the U.S. Supreme Court building in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST) 

Jessica Ingstrum (C) of Chandler, Arizona, and fellow participants stand for the U.S. national anthem before the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS HEALTH CIVIL UNREST) 

Students in shirts spelling out "LIFE" dance along the route of the annual March for Life rally in Washington, January 25, 2013. The anti-abortion marchers on Friday marked the 40th anniversary of the Roe v. Wade U.S. Supreme Court ruling legalizing abortion, and Pope Benedict expressed support for the demonstrators. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS CIVIL UNREST)