From, Sexuality: A Biopsychosocial Approach by Chess Denman, p. 54:
Politicians and the press have created an image of a tidal wave of teen parenthood, caused by young women’s unregulated sexual behaviour and poor women sponging off the state, even though this is unwarranted. In America, for example, teen motherhood cannot be said to have grown as a consequence of welfare because the value of welfare has reduced (Schwartz and Rutter 1998). Interviews with teens who are pregnant do not indicate the kind of planning and forethought necessary for their pregnancy to be a thought-out monetary strategy. Indeed, being able to see a future for oneself is actually associated with abstaining from sex or using contraception (Pipher 1994, in Schwartz and Rutter 1998). In fact, teen pregnancy themselves have not increased at all. Instead they have declined along with the general decline in pregnancy rates but, because they have not declined as much as pregnancy rates in other age ranges, they form a rising proportion of the figures.
However, this may not be all the story, as shown by the following quote taken from the this article on Teenage pregnancy on the UK’s Department for Education and Skills website:
In the 1970s, Britain had similar teenage pregnancy rates to the rest of Europe. But while other countries got theirs down in the 1980s and 1990s, Britain’s rate stayed high. The latest available figures show that Britain’s teenage birth rate is five times that in Holland, three times higher than in France and double the rate in Germany. Other English-speaking countries such as Canada and New Zealand have teenage birth rates higher than ours. In the United States the rate is more than double that in the UK.
In 1999 the Government published a Teenage Pregnancy Report from its Social Exclusion Unit. It acknowledged there was no single cause, but pointed out three major factors: first, that many young people think they will end up on benefit anyway so they see no reason not to get pregnant. Second, that teenagers don’t know enough about contraception and about what becoming a parent will involve. Third, that young people are bombarded with sexual images in the media but feel they can’t talk about sex to their parents and teachers. [emphasis added]