The number of legal abortions in the United States decreased just over 6 percent in the six months after the Supreme Court ended the right to abortion last June, according to a report released Tuesday, the most comprehensive and up-to-date count of abortions nationwide.

The overall decline exceeds what was estimated by some researchers before the Supreme Court ruling. New restrictions and the obstacles they create — including travel logistics and expenses, long wait times at some clinics and confusion or fear about laws — seem to have prevented even more women than expected from obtaining legal abortions.

For many women seeking an abortion, “the barriers that were in place were not surmountable,” said Alison Norris, an Ohio State professor of epidemiology and one of the authors of the report. Though many clinics expanded capacity, she said, “it’s insufficient to manage the losses.”

The data goes through Dec. 31, by which point 13 states had banned abortion with almost no exceptions and another, Georgia, had banned it after six weeks of pregnancy. Legal abortions in the states with total bans fell to nearly zero — an average decrease of around 7,300 abortions a month compared with April and May. They increased by an average of 2,100 a month in states where abortion remained legal, suggesting that some women traveled across state lines. The increase offset only a third of the decrease in the states with bans.

Abortion access is continuing to change. In the coming days, Florida, which allows abortion through the 15th week of pregnancy and has become a destination for women seeking abortions in the South, is expected to ban it after six weeks. And one of the pills in the two-pill regimen for medication abortion, a method that now represents the majority of legal abortions in America, may be curtailed if a federal court ruling in Texas issued Friday is upheld.

The new data overestimates the total reduction in abortions, because it does not include people who obtained abortions outside the U.S. health system, such as by ordering pills online from other countries. Previous estimates suggest more than 6,500 women are requesting pills this way each month. That is more than the total decline in legal abortions, though it is uncertain how many of those requests result in abortions.

The report is from WeCount, a research effort of the Society of Family Planning, which supports abortion rights. It collected abortion counts from 83 percent of clinics, hospitals and telehealth providers in the country. For the places that did not provide data, the group estimated the changes based on historical data and the trends for nearby clinics.

Abortions also fell substantially in states with restrictions that fell shy of complete bans. For example, in Georgia, which outlaws abortions after six weeks of pregnancy, the number of abortions decreased 40 percent. (The earliest date most women can find out they’re pregnant is at four weeks.)

Legal abortions also declined substantially even in places where courts overturned proposed bans. In Arizona, where abortion is allowed through the 15th week of pregnancy, several clinics closed temporarily as courts determined whether an abortion ban that predated Arizona’s statehood could be enforced. The number of abortions a month plummeted 85 percent to 230 between April and July, and rose to 870 by December. In Ohio, a six-week abortion ban went into effect in June, and the number of legal abortions fell 62 percent from before Dobbs, to 790. The ban was overturned in September by a judge, and Ohio now has more than 1,400 abortions a month. Neither state experienced a return to pre-Dobbs levels.

“For our patients, it’s a constant source of fear and confusion to question what and where care is legally available,” said Emily Wales, chief executive of Planned Parenthood Great Plains.

Research has shown that the women most likely to be deterred by long distances are poor, Black or Hispanic. Teenagers, immigrants and people with child care or elder care responsibility are also more affected.

Still, thousands of women traveled long distances to obtain abortions, the data shows. The number of abortions increased substantially in several states that have preserved access and are near states with bans. The largest increases in the number of abortions performed were in Florida, Illinois and North Carolina. States in regions where abortion remains legal, the West Coast and Northeast, did not experience surges.

“While many red states have effectively become abortion-free in the aftermath of Dobbs, there is a long way to go,” said Andrew Shirvell, founder and executive director of Florida Voice for the Unborn, which supports amending the Constitution to ban abortion.

If Florida’s Legislature imposes a six-week ban, as expected, it will most likely decrease abortion access throughout the South. A Woman’s Choice of Jacksonville was on track to see 1,000 more patients this year than last, said Kelly Flynn, the clinic’s founder and president. More than a third of her patients are traveling from out of state, up from fewer than 10 percent before the bans began. Most are past six weeks pregnant.

“Florida has been a lifeline for the South, and if the six-week ban passes, it’s going to be devastating and dangerous for so many people,” she said.

In North Carolina, abortion increased by 24 percent. There, a Democratic governor has stood in the way of new restrictions, but a state legislator recently changed parties, giving Republicans a potentially veto-proof majority.

Even though the WeCount data represents the most complete accounting of legal abortions in America, the researchers acknowledge that missing data from some clinics that have declined to share it may lead to small inaccuracies. There was incomplete data in 23 states. In Florida, the state with the largest increase in abortions in the report, fewer than half the state’s clinics submitted complete numbers to the researchers, requiring them to estimate numbers for the remainder. The data also shows a substantial increase in the number of abortions obtained nationwide in December, a shift that the researchers couldn’t easily explain.

The new report also updates numbers from an August data release, the result of more complete data from clinics that did not participate in the first round of surveys. It showed that the total decline in abortions in the two months after Dobbs was just over half as large as originally published.

“Regardless, this is compelling new evidence that abortion bans are preventing tens of thousands of people who want abortions from reaching providers in the formal health care system,” said Caitlin Myers, a professor at Middlebury College who has studied the effects of abortion restrictions before Dobbs and was not involved in the report.

The measured declines in legal abortions were about twice as large as she had estimated in her research, based solely on increases in travel distances. “It’s likely that factors like clinic congestion, stigma and fear are proving just as great an obstacle,” she said.

Clinics in states near those with bans say that as much as they have tried to expand capacity, it is not enough. In Kansas, where voters rejected a ballot measure in August that would have banned abortion, two new clinics have opened, and abortions since Dobbs have increased by 23 percent.

Trust Women in Wichita now sees more than 500 patients a month, three times as many as before Dobbs, said Zack Gingrich-Gaylord, the clinic’s communications manager. Nearly three-quarters are from out of state, most from Texas. For women in Houston, for instance, Trust Women is the closest clinic, a nine-hour drive away.

After the Dobbs decision, the clinic hired half a dozen more doctors and tripled its staff to 24. It renovated its buildings and upgraded its phone lines. Still, on a recent Monday, the clinic received 16,000 phone calls — one number called 250 times.

More patients at the clinic than before are in their second trimester because of the challenges of getting to a clinic. A majority rely on funds from nonprofits that help arrange and pay for travel.

Planned Parenthood Great Plains, which had to stop providing abortion care in its Arkansas, Missouri and Oklahoma locations, opened a third clinic in Kansas and started providing telehealth services. More than half its patients are now from out of state. Still, said Ms. Wales, its chief executive, the need across the region is too high.

“The simple answer is that we are not able to meet demand,” she said.

Allison McCann and Francesca Paris contributed reporting and graphics.