The analysis, which looked at six states that introduced parental involvement laws in the last decade and is believed to be the first study to include data from years after 1999, found instead a scattering of divergent trends.
For instance, in Tennessee, the abortion rate went down when a federal court suspended a parental consent requirement, then rose when the law went back into effect. In Texas, the rate fell after a notification law went into effect, but not as fast as it did in the years before the law. In Virginia, the rate barely moved when the state introduced a notification law in 1998, but fell after the requirement was changed to parental consent in 2003.
Since the United States Supreme Court recognized states' rights to restrict abortion in 1992, parental involvement legislation has been a cornerstone in the effort to reduce abortions. Such laws have been a focus of divisive election campaigns, long court battles and grass-roots activism, and are now in place in 34 states. Most Americans say they favor them.
"It's one of the few areas that the U.S. Supreme Court has allowed states to legislate, so it's become a key for lowering the abortion rate," said Mary Spaulding Balch, director of state legislation for the National Right to Life Committee. Ms. Balch said she believed that consent laws were effective.
Yet the Times analysis of the states that enacted laws from 1995 to 2004 * most of which had low abortion rates to begin with * found no evidence that the laws had a significant impact on the number of minors who got pregnant, or, once pregnant, the number who had abortions.
A separate analysis considered whether the existence or absence of a law could be used to predict whether abortions went up or down. It could not. The six states studied are in the South and West: Arizona, Idaho, South Dakota, Tennessee, Texas and Virginia. (A seventh state, Oklahoma, also passed a parental notification law in this period, but did not gather abortion data before 2000.)
Supporters of the laws say they promote better decision-making and reduce teenage abortions; opponents say they chip away at abortion rights and endanger young lives by exposing them to potentially violent reaction from some parents.
But some workers and doctors at abortion clinics said that the laws had little connection with the real lives of most teenagers, and that they more often saw parents pressing their daughters to have abortions than trying to stop them. And many teenagers say they never considered hiding their pregnancies or abortion plans from their mothers.
"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.
Phillip B. Levine, an economics professor at Wellesley College, examined nationwide survey results from 1985 to 1996, a time when many parental involvement laws were put in place, and found that the laws were associated with about one-eighth of the total drop in minors' abortions in those states. Much of the drop was associated with other factors, which might include the economy, availability of abortion, changes in mores and other trends. "It's not surprising it's not popping out," Dr. Levine said of the small drop found in the Times analysis. "There is nothing overwhelmingly staggering" in the change associated with the laws.
Supporters of parental involvement laws say they allow parents to help their children make an important health care decision, as parents would on any other surgical procedure.
For Cathi Harrod, interim president of the Center for Arizona Policy, who lobbied for 15 years for her state's parental consent law, getting minors to involve their parents in their medical decisions was reason enough for the laws, whatever the impact on overall abortion rates. Arizona's law went into effect in 2003.
Ms. Harrod said she believed that there was a groundswell of women who have had regrets about their own abortions and that as they made their feelings known, "we think the numbers will go down as minors learn more about their options." Either way, she said, her organization will push for stricter standards and more public accountability for judicial bypass through access to judges' records.
But providers interviewed in 10 states with parental involvement laws all said that of the minors who came into their clinics, parents were more often the ones pushing for an abortion, even against the wishes of their daughters.
"I see far more parents trying to pressure their daughters to have one," said Jane Bovard, owner of the Red River Women's Clinic in Fargo, N.D., a state where a minor needs consent from both parents. "As a parent myself, I can understand. But I say to parents, 'You force her to have this abortion, and I can tell you that within the next six months she's going to be pregnant again.' "
Renee Chelian, director of Northland Family Planning Centers in the Detroit area, said she had had to call the police on parents who wanted their daughters to have abortions, "because they threaten physical violence on the kids."
Ms. Chelian added that the laws might have unseen effects, including driving some teenagers to try to abort their pregnancies on their own.
"Kids talk among themselves," she said. "When we tell them they need to go to court or tell their parents, that's when they tell us there's a Web site" for chemicals or herbal remedies that claims to induce abortions.
Nearly all state parental involvement laws allow for minors to bypass their parents by going through a judge. Providers interviewed in 10 states all said that the process was generally not cumbersome, but that some girls would be afraid to go to court.
For Nicole, the 16-year-old in the Allentown clinic, the hard part was telling her estranged father.
"It was my choice to tell him," she said. "It hurt him, but he understands and is there for me. So in a way it brought us closer together."