BOSTON Abortion pills pose no apparent risk to a woman who later decides to have a child, according to a study of nearly 12,000 women in Denmark who had a chemical or surgical abortion.
The study in the New England Journal of Medicine found no difference in the rates of subsequent tubal pregnancies, miscarriages, premature births or low birthweight births for women who had previously had surgical abortion, usually through vacuum aspiration, or those taking any of the three drug regimens that eliminate a fetus.
About 2.4 percent of later conceptions led to tubal pregnancy and just over 12 percent miscarried, regardless of the type of earlier abortion, the researchers found.
The likelihood of having a premature birth (5.4 percent) or a low birthweight baby (4 percent) was slightly lower among the women who had received the abortion pill but the difference was not statistically significant.
"The short-term safety of medical abortion has been well established," said Dr. Jun Zhang of the National Institute of Child Health and Human Development, who worked on the study.
Zhang said the new study is the most comprehensive look to date of the long-term impact of abortion pills.
"We identified all women living in Denmark who had undergone an abortion for non-medical reasons between 1999 and 2004 and obtained information regarding subsequent pregnancies from national registries," his team wrote.
The team only looked at the first pregnancy after the abortion. "We didn't have the data to look at second and third pregnancies," Zhang said.
Abortion using drugs as opposed to surgery has become increasingly common. From its approval in the U.S. in 2000 to 2004, 360,000 women used the abortion drug combination of mifepristone and misoprostol.
The study did not compare complication rates between abortion pill users and women who had never had an abortion.
"Many studies have concluded that surgical abortion in the first trimester does not increase the risk of ectopic pregnancy, spontaneous abortion, preterm birth, or low birth weight in subsequent pregnancies," the researchers wrote.
In addition, women who have never had an abortion tend to have a different pattern of income, smoking rates and other health-related behaviors that would make a comparison difficult, the researchers said.
The abortion pill fails, and a surgical abortion is necessary, in about 1 out of 14 cases.