Washington ? Students who took part in sexual abstinence programs were just as likely to have sex as those who did not, according to a study ordered by Congress.

Also, those who attended one of the four abstinence classes that were reviewed reported having similar numbers of sexual partners as those who did not attend the classes. And they first had sex at about the same age as other students – 14.9 years, according to Mathematica Policy Research Inc.

The federal government now spends about $176 million annually on abstinence-until-marriage education. Critics have repeatedly said they don’t think the programs are working, and the study will give them reinforcement.

However, Bush administration officials cautioned against drawing sweeping conclusions from the study. They said the four programs reviewed – among several hundred across the nation – were some of the first established after Congress overhauled the nation’s welfare laws in 1996.

Officials said one lesson they learned from the study is that the abstinence message should be reinforced in subsequent years to truly affect behavior.

“This report confirms that these interventions are not like vaccines. You can’t expect one dose in middle school, or a small dose, to be protective all throughout the youth’s high school career,” said Harry Wilson, commissioner of the Family and Youth Services Bureau at the Administration for Children and Families.

Mathematica’s study could have serious implications as Congress considers renewing this summer the block grant program for abstinence education known as Title V.