"I would have told my mother anyway," said a 16-year-old named Nicole, who waited recently at a clinic in Allentown, Pa., a state that requires minors to get the permission of just one parent. Nicole's mother and father are divorced, and it was her mother she went to for permission to have an abortion.

"She was the first person I called," Nicole said. "She's like a best friend to me."

Abortion rates have been dropping nationwide since the mid-1980's, most precipitously for teenagers. But in three states -- Arizona, Idaho and Tennessee -- the percentage of pregnant minors who had abortions rose slightly after the consent laws went into effect.

When the Times study compared the first full year after a state began enforcing a parental law with the last full year before the law, it found that abortions among minors dropped an average of 9 percent. But in the same period, the rates for pregnant 18- and 19-year-olds, who were not affected by the law, dropped by 5 percent, suggesting that most of the drop among minors was associated with other factors that affected minors and adults alike.

"There are ongoing trends that are pushing both birth rates and abortion rates down significantly, and those larger trends are more important than the effect of these laws," said Ted Joyce, an economist at Baruch College in New York who has studied parental involvement laws. He found they had limited effects on small subgroups of minors but little impact over all.

Of the remaining decline in teenage abortion rates in the Times study, Dr. Joyce said that some of it might be attributed to minors going out of state for abortions. The health departments in these states do not track data on such abortions, but in three previous studies of states where such data were available, completed before 1991, two found that any drop in minors' abortions was matched by an increase in minors getting abortions out of state.

Previous research on the effects of parental notification laws has been slender and has produced contradictory conclusions. All were hampered by inconsistencies in the ways states gather and report data.

The Times analysis was limited by its focus on just six states, but it avoided the possible distortions of including states that gather data in inconsistent ways.