Teen pregnancy contagious to sisters: Study

By Dr. Ananya Mandal, MDAug 10 2011

According to a new study teenage pregnancy and motherhood is contagious within families. Scientists have discovered that the sister of a teenage mother is twice as likely to follow in her footsteps as a girl with no family experience of early motherhood.

They call it “peer effect” on girls aged 16 to 19 which they say has a far more powerful impact than any education or advice they are given at school. It was most pronounced when the sisters were close in age.

The study, conducted by researchers at Bristol University, may help to explain why the previous government’s Teenage Pregnancy Strategy was a failure. Despite a £280million investment and a much-trumpeted advertising campaign to promote contraception, Britain still has the highest teenage pregnancy rate in Europe. Figures released by the Office for National Statistics in February showed that in 2009 – the most recent year for which there are records – the rate of conception among UK women under 18 was 38.3 per 1,000 girls, just 17 per cent down from 46.6 in 1998.

For this study the team looked at census figures from 42,606 women in Norway in the 1960s, as its data is unique in linking teenage pregnancy with family relationships. The study found that if a girl became a teenage mother, the probability of her nearest younger sister doing the same increased from a one-in-five chance to two in five.

Higher education levels and a more affluent family background have tended to lower rates of teenage pregnancy in developed countries. But Professor Carol Propper, who led the study, said, “These findings provide strong evidence that the contagious effect of teen motherhood in siblings is larger than the general effect of being better educated… The message is that what you do in school is not enough to counteract the effect of siblings, and that needs to be accounted for in public policy. It needs to focus more on what’s going on in families.” Anastasia de Waal, deputy director at Civitas thinktank, said some aspects of the British experience did resonate with the study, “It is interesting that girls who lack employment and education opportunities see teenage pregnancy as an alternative. So I am not surprised that this study shows teenage pregnancy might look appealing to a younger sister because it is doable.”