NEW YORK (REUTERS) - The percentage of US teenagers who have had sex has dropped significantly over the past quarter-century, with less than half of 15- to 19-year-olds reporting they had a sexual experience, according to US data released on Wednesday.

Some 44 per cent of never-married females in that age group reported having had sex at least once, down from 58 per cent who said they had done so in a survey released in 1988, according to data by the National Centre for Health Statistics.

The prevalence of sexual activity among teen males also dropped to 47 per cent from 69 per cent over the same period.

The centre's National Survey of Family Growth survey of 1,037 female and 1,088 male American teenagers, conducted from 2011 through 2013, showed boys were more likely to become sexually active in their early years than girls.

By for late teens, the percentage of teenagers who had sexual intercourse was similar for both genders.

The study found teenagers were using most forms of contraceptives at similar rates as they did over the past decade.

Condoms remained the most common form of contraception for teenagers.

While the number of teens using the birth control pill and withdrawal contraceptive methods during their first sexual experiences remained the same, the use of the so-called morning-after pill increased to 22 per cent from 8 per cent.

The study also looked at teenage pregnancy rates tied to contraceptive use.

In 2013, the US birth rate for 15- to 19-year-olds dropped by more than half since its peak in 1991, but the rate was still higher than in other developed countries.

Girls who did not use some form of contraception the first time they had sex were twice as likely to become a mother in their teenage years as those who used a method.