A worrying number of young people who do use condoms don't use them correctly, so risking unwanted pregnancy or infections, reveals research published ahead of print in the journal Sexually Transmitted Infections.
But a good relationship with their mothers seemed to be associated with correct condom use, the research showed.
The authors carried out a survey of the sexual activity of almost 1400 teenagers aged between 14 and 18 from 21 different schools and colleges across England.
Around half of the respondents said that they had had penetrative vaginal sex, and almost two thirds (373) saying that they had used a condom on the most recent occasion.
Among these 373, 6% said they had applied a condom after penetration and 6% said they continued to have penetrative sex after they had removed the condom.
Just over 100 respondents also kept a sexual activity diary for six months. Of the 74 who said they had used a condom, almost one in three had put it on too late, and almost one in 10 had removed it too soon, on at least on occasion during that period.
And 322 of the 714 diary entries described sexual encounters in which a condom had not been used during penetrative vaginal sex.
Among those keeping a diary, the primary reasons given for not using a condom were to enhance intimacy, that sex felt better without, that other contraception was being used, or that they got carried away.
The three most common reasons for actively choosing to use a condom were to avoid pregnancy, avoid making a mess, and to make sex last longer. Few gave the prevention of sexually transmitted infections as a reason.
Those who used other forms of contraception were more than three times as likely to use condoms incorrectly, while those who did not use condoms routinely were also more likely to use them incorrectly.
But the research also showed that those who reported a close relationship with their mothers were more likely to use them correctly.
"If we are to see a reduction in [sexually transmitted infection] prevalence, it is essential that young people understand the importance of using condoms consistently and correctly, and are also equipped with the skills and knowledge to do so," conclude the authors.
[England Online First Sex Transm Infect 2006; doi: 10.1136/sti.2006.021410]