One in ten women who continued her studies at sixth-form college or university had been pregnant at least once before graduation, and three-quarters of these pregnancies were unplanned, the study of more than 1,000 women found.
Conducted by the National Union of Students, the research suggests that more educated women are more likely to become pregnant than those who leave school at 16.
The national average for conceptions among females aged between 15 and 19 is lower than the rate discovered in the study, at one in 16.
"People assume that students who go into further education are more informed...This research debunks that myth. Contraceptive advice has been neglected for too long," said Alison Hadley, a policy adviser for Brook Advisory Centre, a service for women under 25.
One in five of the students who attended further education colleges in England and Wales occasionally or often had sexual intercourse without using contraception, the study found. Students responding to the survey were not asked whether their pregnancies were aborted or completed. Ms Hadley said: "It is possible that more of these women will have chosen not to carry on the pregnancy because of their future careers, so it is likely there are fewer teenage single mothers among this group."
The findings come after recent government figures revealed that more women aged between 20 and 24 have abortions than any other age group.
The study said that better education for young women about contraception and the risks of sexually transmitted disease and unplanned pregnancy was needed.
Andrew Pakes, president of the NUS, said: "We strongly recommend that students protect themselves against pregnancy and sexually transmitted infections. Our survey found that many students were doing neither. The NUS will be seeking to redress the balance and get accurate information directly to students. In the light of the findings, the union will be campaigning with pregnancy advice groups to improve education for students."
The findings showed that while 37 per cent said they received informal education at home about sex, only 22 per cent said their parents told them anything about how to avoid becoming pregnant.
One in 20 of the students said they "often" had unprotected sex, and 17 per cent said they did so "occasionally". Of these, 38 per cent said they had casual sex "often" and 40 per cent said they did not use the Pill because they were not in a long-term relationship
Toni Belfield, of the Family Planning Association, said: "The point is not whether, where, how or with whom women should be having sex; it is about enabling women to make informed decisions."Reuse content