In the United Kingdom, sex education is only compulsary in High Schools, and even then, student's parents can still refuse to allow their children to take part in the lessons. As knowledge of staying healthy has improved, young people are starting puberty earlier and earlier, therefore children need to know about this sooner than they usually do now. Also, teenage pregnancies are associated with many social issues, including lower educational levels, higher rates of poverty, and other poorer life outcomes in children of teenage mothers. The United Kingdom has the second highest rates of teenage pregnancies in the whole of the world, and in countries such as Norway and Sweden where sex education begins at the age of seven or eight, compared to eleven or twelve in the United Kingdom, teenage pregnancy rates are significantly lower.