Alaska Gov. Sarah Palin (file photo)

U.S. Republican vice presidential candidate Sarah Palin says her unmarried 17-year-old daughter is pregnant.

In a statement released Monday, Palin and her husband, Todd, say Bristol Palin is about five months pregnant and will keep the child.

The Palins say they are proud of her decision and even prouder to become grandparents.  They add that Bristol plans to marry the child's father.

Sarah Palin, who is also the Governor of Alaska, has been lauded by fellow social conservatives for her strong opposition to abortion and her support of abstinence-until-marriage sex education.

Senior officials from the campaign of Republican Presidential Candidate John McCain say he and his top aides were aware of Bristol's pregnancy before selecting Palin as his running mate.

Democratic Party presidential nominee Barack Obama urged reporters to back away from the story. Obama said people's families, and especially their children, are off limits.  Obama said he would fire any campaign staffer if he thought they were spreading the story.

The Palins have asked the media to respect the young couple's privacy.

A U.S. organization on teen pregnancy, The National Campaign to Prevent Teen and Unplanned Pregnancy, said in a statement Monday that U. S teen birth rates are on the rise for the first time in 15 years and that, at present, 3 in 10 girls in the United States become pregnant by age 20.