Washington: Despite considerable efforts to reduce teen pregnancy, youngsters are still having sex without any contraceptive use, a new study has found.

There was a significant decline in the number of teen pregnancies in 1990s and early 2000s, but the trend eventually reversed between 2003 and 2007, said Dr John S. Santelli, professor and chair of the Heilbrunn Department of Population and Family Health at Columbia University Mailman School of Public Health.

Between 1991 and 2003, teens'' condom use increased, leading to a decreased risk of pregnancy and to declines in teen pregnancy and childbearing.

"After major improvements in teen contraceptive use in the 1990s and early 2000s, which led to significant declines in teen pregnancy, it is disheartening to see a reversal of such a positive trend," said Santelli.

"Teens are still having sex, but it appears many are not taking the necessary steps to protect themselves from unwanted pregnancy or sexually transmitted infections," he added.

The authors suggest that the recent decline in teen contraceptive use since 2003 could be the result of faltering HIV prevention efforts among youth, or of more than a decade of abstinence-only-until-marriage sex education that does not mention contraception unless it is to disparage its use and effectiveness.

They said that reversal in contraceptive use is consistent with increases in the teen birth rate in 2006 and 2007 as reported by the Centres for Disease Control and Prevention (CDC), and may well portend further increases in teen pregnancies and births in 2008.

The authors recommend reinvigorated efforts at both the state and national levels to promote contraceptive use among teens through medically accurate sex education and increased access to health services, to effectively address the problem of teen pregnancy.

The new findings appear in the Journal of Adolescent Health.