Seoul, Jan 3 (IANS): Teenagers who experience their first sexual intercourse at an early age run a greater risk of contracting sexually transmitted infections (STIs) which includes diseases such as gonorrhea, syphilis, chlamydia, HIV or other infection, warns a study.

Sexually transmitted infections are major causes of medical and psychological problems globally.

"This study shows that earlier initiation of sexual intercourse increases the odds of experiencing STIs," the researchers said.

"Also as the age gap gets shorter, the odds of experiencing STIs increase. Our study suggests that it is important to consider the time period of first sexual intercourse and to reinforce a monitoring system along with the development of other preventive strategies," the study said.

For the study, the researchers from Yonsei University in Seoul used data from a Korean national survey of youth risk behaviours that is conducted annually by the Korean Centres for Disease Control and Prevention.

Responses of 22,381 adolescents with sexual intercourse experience were included for the analysis.

Approximately 7.4 percent of boys and 7.5 percent of girls reported having STI. The researchers found that for both boys and girls, the chance of experiencing STIs increased as the age of first sexual intercourse decreased.

Compared to teens who had first intercourse in 12th grade, those whose first experience was in seventh grade were three times more likely to have had an STI, youthhealthmag.com reported.

The findings appeared in the Journal of Sexual Medicine.