Young women who have sex at an early age are more likely to develop cervical cancer, a study of 20,000 women has found.
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The finding came after experts at the International Agency for Research on Cancer investigated why poorer women have a higher risk of the disease.
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Until now, experts thought that the difference in cases of the disease could be just because poorer women were less likely to go for cervical screening.
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But researchers now think the difference is largely because poorer women start having sex an average of four years earlier.
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Cervical cancer is largely triggered by the presence of the human papillomavirus (HPV) - which is sexually transmitted.
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Study's lead author, Dr Silvia Franceschi, said the findings were not restricted to adolescence and the risk of cervical cancer was also higher in women who had their first sexual intercourse at 20 rather than 25 years.
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"In our study, poorer women had become sexually active on average four years earlier," the BBC quoted Franceschi as saying.
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"So they may have also been infected with HPV earlier, giving the virus more time to produce the long sequence of events that are needed for cancer development," Franceschi added.
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Dr Lesley Walker, director of cancer information at Cancer Research UK, said the study raised some interesting questions.
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"Although women can be infected by HPV at any age, infections at a very young age may be especially dangerous as they have more time to cause damage that eventually leads to cancer.
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"Importantly, the results back up the need for the HPV vaccination to be given in schools at an age before they start having sex, especially among girls in deprived areas."
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The findings are published in the British Journal of Cancer.