Put differently, America is estimated to have some 750,000 teenage pregnancies a year.

According to America's leading health agency, the Centers for Disease Control and Prevention (CDC): "About one-third of girls in the United States get pregnant before age 20."

The US offers government funding for health education programmes that promote sexual abstinence until marriage, although US lawmakers were investigating earlier this year whether to cut the funding.

Opponents of abstinence education say the approach ignores the fact that teenagers are sexually active and fails to give them accurate medical information or advice on safer sex.

Governor Palin herself has said she opposes funding sexual-education programmes in Alaska and has supported abstinence programmes in schools.