Mar. 23 -- FRIDAY, March 30 (HealthDay News) -- Women can take the two components of the so-called "abortion pill" simultaneously, rather than 24 hours apart, as is typically done, a new study found.

And a second study found the drug is safe for late first-trimester abortions.

Mifepristone, or RU486, aborts a pregnancy by blocking the production of the hormone progesterone. When the drug is used alone, materials linked to conception can remain in the uterus, posing a risk of infection. That's why doctors also prescribe misoprostol, which causes the uterus to contract and safely expel this material.

Both studies are published in the April issue of Obstetrics & Gynecology.

The first study found that giving mifepristone and misoprostol vaginally at the same time is at least as effective for abortion as spacing the doses 24 hours apart.

"It really gets down to convenience for the woman," said study author Dr. Mitchell Creinin, director of gynecologic specialties at the University of Pittsburgh. "We used to have a world where women who wanted to have medications for abortion would have to go through a process over multiple days. It (simultaneous dosing) gives women flexibility. It doesn't mean they need to do it this way, but it opens up a time window."

For this trial, 1,128 women took mifepristone orally and were then randomly selected to either take misoprostol vaginally immediately in a doctor's office or 24 hours later at home.

The rate of complete abortions was similar in both groups and did not differ by how far along a woman was.

The second study looked at 321 women who were 64 to 84 days pregnant. They were from Rochester, N.Y., Ho Chi Minh City, Vietnam, and Pune, India. The women received misoprostol vaginally 24 to 48 hours after taking mifepristone. Up to two additional doses of misoprostol were administered orally or vaginally as needed.

Eighty-nine percent of the women successfully terminated their pregnancies. Most women also reported that they were satisfied (64.8 percent) or very satisfied (28.6 percent) with the experience. Almost all (94 percent) said they would recommend the procedure to a friend. Most (90.4 percent) also said they would opt for a medication abortion if they required another procedure in the future.

Some 55 percent of the 1.3 million abortions performed in the United States each year occur before nine weeks of gestation. An additional 34 percent of abortions occur in women who are 10 to 12 weeks pregnant. Surgical abortion during this time period is effective but not always available. And that procedure can carry significant health risks, the researchers said.

This second study shows that a medical alternative to surgical abortion is safe and effective, the researchers said.

"Medical abortion has been routinely used for early first trimester abortions but not so often for the later end of that trimester," said study lead author Hillary Bracken, a program associate with Gynuity Health Projects in New York City. "Now, with other studies, it is well established that this is an effective and acceptable option for women."

More information

For more on the abortion pill, visit the U.S. Food and Drug Administration.

SOURCES: Mitchell D. Creinin, M.D., director of gynecologic specialties, University of Pittsburgh; Hillary Bracken, program associate, Gynuity Health Projects, New York City; April 2007, Obstetrics & Gynecology