August 16 (HealthDay News) -- A medical abortion is unlikely to affect a woman's future reproductive health, a new study reports.

The research, which appears in the Aug. 16 issue of the New England Journal of Medicine, found that abortions induced by medication don't increase the risk of ectopic pregnancy, miscarriage, preterm birth or low birth weight babies in future pregnancies any more than surgical abortions do.

There are three different methods of medical abortion: a drug called misoprostol used alone; methotrexate followed by misoprostol; and mifepristone followed by misoprostol. The combination of mifepristone and misoprostol is the one most commonly used, according to the study. Mifepristone received approval from the U.S. Food and Drug Administration for use in medical abortion in 2000. By 2004, about 360,000 American women had undergone medical abortions, and the use of medical abortion is likely to increase, the study authors wrote.

While there have been many previous studies on the long-term safety of surgical abortion, most of the studies done on medical abortion have assessed only the short-term safety and side effects related to medical abortion. Little research has been done on subsequent pregnancies after medical abortion, according to the report.

For the current study, the researchers turned to Denmark, which maintains a national registry with information on abortion and subsequent pregnancies. The researchers identified nearly 12,000 women who'd had a first-trimester abortion for non-medical reasons, who then went on to have a future pregnancy. From that group, 2,710 had undergone medical abortion and 9,104 had undergone surgical abortion.

The rates of ectopic pregnancy in subsequent pregnancies were 2.4 percent for medical abortion and 2.3 percent for surgical abortion. The rate of miscarriage was 12.2 percent for the medical abortion group and 12.7 percent for the surgical group. Rates of preterm labor and low birth weight babies were also lower for the medical abortion group compared to the surgical abortion group.

Even after adjusting for maternal age, gestational age and socioeconomic status, the researchers didn't find any statistically significant difference in complications of future pregnancies between the medical and surgical abortion groups.

"Mifepristone medication abortion is a safe, effective option for early pregnancy termination, and this study provides Planned Parenthood with valuable information for our doctors and our patients," said Dr. Vanessa Cullins, vice president for medical affairs for the Planned Parenthood Federation of America.

"The data from this study shows health-care providers and women that medication abortion compares very well with surgical abortion for safety and effectiveness for women who want to plan healthy pregnancies in the future," she added.

"Medical termination is definitely easier for women, and patients can be reassured that it's safe and isn't experimental," said Dr. Miriam Greene, an obstetrician and gynecologist at New York University Medical Center.

But, she added, "Women still have to be careful and use contraception and practice safe sex."

SOURCES: Miriam Greene, M.D., obstetrician/gynecologist, New York University Medical Center, clinical assistant professor, obstetrics and gynecology, New York University School of Medicine, and author, Frankly Pregnant: A Candid, Week-by-Week Guide to the Unexpected Joys, Raging Hormones, and Common Experiences of Pregnancy, New York City; Vanessa Cullins, M.D., M.P.H., vice president, medical affairs, Planned Parenthood Federation of America; Aug. 16, 2007, New England Journal of Medicine