Impact of abortion pills studied

Women who use abortion pills rather than the more common surgical method seem to face no greater risk of tubal pregnancy or miscarriage in later pregnancies.

The federally funded research -- based on nearly 12,000 Danish women -- is considered the best study to date of the impact of this newer abortion method on subsequent pregnancies.

The vast majority of abortions are called surgical abortions, usually done by vacuuming an embryo or fetus out with a syringe or electric pump.

Medical abortions, usually using mifespristone -- formerly known as RU-486 -- and misoprostol, make up about 8 percent to 10 percent of the roughly 1.3 million abortions in the United States.

While previous research has shown surgical abortions don't increase the risk of problems in later pregnancies, little research had been done into the impact of medical abortions.

Abortions done with pills may leave bits of placenta or other embryonic material in the uterus, and some doctors have wondered whether that might interfere with subsequent pregnancies, said Dr. Matthew Reeves, a reproductive medicine expert at the University of Pittsburgh School of Medicine.

"This kind of squashes any concerns," said Reeves, who was not involved in the study.

The paper is published in the current New England Journal of Medicine.

In the new study, researchers used a national abortion registry to identify all women in Denmark who had abortions between 1999 and 2004, and then got information on later pregnancies from national patient and birth registries.

Denmark is the only country with an abortion registry, said study co-author Dr. Jun "Jim" Zhang of the National Institutes of Health.

They looked at tubal pregnancies, in which a fertilized egg implants outside the uterus -- usually in the fallopian tubes. Such a situation fails to nurture the embryo and endangers the mother.

The new study found tubal pregnancies occurred at the same frequency -- about 2.5 percent of the time -- in both the medical and surgical groups. The rates of miscarriage, early deliveries and low birth weight babies also were similar.