That's up from 36 percent who said they used an oral contraception as their primary form of birth control in 2011-12, said the Health & Social Care Information Center, which collects and analyzes health and social data in Britain.
The information center reported condoms were the contraceptive method of choice for 40 percent of young teenage women who used the clinics in the past year, down from 46 percent in 2011-12, The Daily Telegraph reported.
However, the total number of teenagers -- and people of all ages, who used clinics -- declined this year in what experts said could be a sign more are receiving contraception over the counter in drug stores, or from their primary care physician.
A total of 17,100 girls age 15 and younger and 268,000 teenagers in total used the clinics this year, down from 20,200 and 283,700, respectively, the previous year, the information center said.
"Our data only deals with people using the National Health Service community contraception clinics and it is important to recognize that contraception is also available via other methods such as a primary care physician and many can now be bought over the counter," Paul Eastwood, who compiled the information center's report, told the Telegraph.
"Last year it was 15-year-olds where oral contraception became the most popular, this year it is more popular for under-15s as well."
Long-acting reversible contraceptives, such as implants, are becoming more popular in all age groups last year with almost 1-in-3 women who visited the clinics requesting them, Eastwood said.