Condoms can protect against STI's and prevent unwanted pregnancies.

The US Food and Drug Administration (FDA) has approved smaller condoms for use after recent studies showed that the 6.69-inch (17cm) minimum length requirement is actually longer than the penis of an average American male.

Health officials have been desperately trying to improve the country's low rate of condom usage - an issue that was highlighted by recent research backed by the Centers for Disease Control and Prevention (CDC) which found that only a third of American men reported using them during sex.

According to the CDC, condoms which did not fit properly and slipped off were cited as one of the main reasons for refusing to wear them.

To try and encourage use, the FDA has changed its policies to allow condoms to be sold which are shorter than the previous minimum length requirement. A recent study of 1,661 American men conducted by Indiana University found that the average penis length was only 5.57 inches.

Boston-based company, Global Protection Corp., which pushed the FDA to approve smaller condoms, has begun selling customized condoms in 60 different sizes, with lengths ranging from 4.9 to 9.4 inches. By comparison normal condoms are usually 6.7 to 8.3 inches long.

David Wedel, the president of Global Protection Corp, said condoms have an image problem and that men's negative perception of smaller condoms could mean they refuse to use them.

"If they bought a small condom before and it was still too big, it's horrible for men to have that experience," Wedel told the New York Times.

Others are also trying to make condoms more appealing: The Bill and Melinda Gates Foundation has given out millions of dollars in grants to groups that are trying to achieve this goal.

Condoms are the only type of contraception that can prevent both pregnancy and protect against sexually transmitted infections.