Sex at a young age was associated with a doubled risk of developing cancer of the cervix.
Examination of the poorest because women have a higher risk of disease, were more likely to have sex about four years earlier than more affluent women.
Previously, he assumed that these differences are due to poor integration of control in the poorer areas, however, the study found that it was the most important factor.
The latest results were published in the British Journal of Cancer.
Although the difference in the incidence of cervical cancer between rich and poor – in the world – established for many years, it was unclear why.
Mainly because it appeared in the rates of infection with human papillomavirus (HPV) – sexually transmitted infections, the vast majority of cases of cervical cancer – are similar in all groups.
The study, conducted by the International Agency for Research on Cancer, which confirms nearly 20,000 women, not the highest rates of cervical HPV lead to higher levels are.
But what can not prove is that the risk was twice as high for women especially poorer backgrounds, said sex at an earlier age.
The age at which she had her first son was a major factor.
Screening was found to affect the level of risk.
However, the number of sexual partners a woman has, and smoking did not take into account the difference.
The researchers, Dr. Silvia Franceschi said the results are not limited to adolescence and risk of cervical cancer was also observed in women who have their first sex at 20 instead of 25.
In our study, poor women sexually active, on average, four years earlier.
This may have been infected with HPV to produce more virus transmission time in a long series of events that are necessary for cancer development. Dr Lesley Walker, director of cancer information, Cancer Research UK, said the study has some interesting questions.
Although women have HPV infection infections of any age can a young age, particularly dangerous because they have more time to cause damage, which ultimately leads to cancer.
It is important that the results are once again the need for the HPV vaccine in schools, at a time before they start having sex, especially for girls in disadvantaged areas.