Making the morning-after pill available to buy in chemists has not encouraged unsafe sex, say experts.
Cutting the cost may increase uptake further
Opponents had claimed there would be a surge in risky sexual behaviour and sexually transmitted infections.
Researchers at Imperial College London found no change in condom use after the emergency pill became available over the counter in January 2001.
Neither had more people used the emergency pill, they told the British Medical Journal.
"These results suggest that the predicted rise in unsafe sex has been overstated and supports the case for lifting the ban on over the counter sales in the US and other countries," said lead researcher Dr Cicely Marston.
Her team looked at survey responses from women aged 16-49 in 2000, 2001 and 2002 who were asked about their sex lives.
Each year, there were about 2,000 responses. Based on these, the researchers were able to gauge that there had been no significant change in contraceptive use among the women.
One in five women said they used condoms, a third used the oral contraceptive pill, a coil or hormone implants and about one in 10 said they used no method.
The number of women who said they used the morning-after pill did not change over the three years studied - around 8% of the women or 160 in each of the years. However, where they got it from did.
A smaller number went to see their GP or local NHS clinic to get the emergency contraception and more chose to buy it from a local chemist after it became available over the counter.
The type of women who used it also changed slightly.
Price tag too high
Overall, younger, single women were most likely to report having used it
There was a slight increase in use among 16-19 year olds in 2001 when the change in availability of the emergency pill was made, but this dropped back down again in 2002.
However, it did not increase the proportion of women using the drug more than once during the year.
The only thing predicting whether or not women would buy emergency contraception over the counter was income.
Women with the highest incomes were over five times as likely to report having obtained their contraception in this way.
Dr Marston and colleagues said cost could be a barrier to some women and that lowering the price tag might increase uptake, particularly among women from lower income groups.
Jan Barlow, Chief Executive of Brook, the sexual health charity for young people, said: "This study provides a strong argument for making emergency contraception available over the counter free of charge to anyone who needs it, including those under the age of 16.
"The current cost of around £25 is prohibitive for some, particularly younger women, and if someone has had unprotected sex it is important that they can get hold of emergency contraception as quickly and easily as possible.
"There is no evidence that making emergency contraception easily available means people will be less responsible about other forms of contraception or use emergency contraception more often."
A spokesman from the Society for the Protection of Unborn Children said the study appeared to be poorly targeted and based on poor methodology.