Condoms that do not fit right could break and may reduce sexual pleasure for both partners, suggesting reasons why men and women often fail to use them, researchers reported.
The study has implications for countries trying to encourage people to use condoms to reduce the risk of Aids, other sexually transmitted infections and unwanted pregnancy, the researchers reported in the journal Sexually Transmitted Infections.
"Men and their female sex partners may benefit from public health efforts designed to promote the improved fit of condoms," Dr Richard Crosby of the University of Kentucky and Dr. Bill Yarber of the Kinsey Institute for Research in Sex, Gender and Reproduction in Indiana wrote.
They surveyed 436 men aged 18 to 67 for their study.
Nearly half - 45 percent - said they had used a badly fitting condom during the previous three months.
These men were more than 2 1/2 times as likely to say the condom broke or slipped when they used it. They also often reported it was irritating to wear.
The men who wore poorly fitting condoms were twice as likely to say that using one reduced sexual pleasure for themselves and their partners.
The findings may make some people giggle, but the researchers said the implications were serious. Men will often not buy condoms sized "small" or even "medium," they said.
"Moreover, the increased likelihood that men using ill-fitting condoms will remove condoms before sex ends constitutes another form of condom failure. Fortunately, it seems likely that these problems could be rectified through education programs," the researchers wrote.
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