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Modern medical abortions not associated with later preterm births, study finds

PLOS
From the study: After medical abortions were introduced in Scotland in 1992, the increased risk of preterm births dropped to 10 to 20 percent. And starting in 2001, after mifepristone became used in medical abortions, Scottish women who had an abortion were no longer more likely to give birth prematurely during later pregnancies than women who had never had an abortion.

A new study from Britain may help end a long-running dispute about whether having an abortion raises a woman’s risk of delivering a baby prematurely (before 37 weeks of gestation) during subsequent pregnancies.

The study’s findings suggest that although some types of surgical abortions may be a risk factor for later premature births, medical abortions are not. 

The implications of the findings are political as well as health-related, for they come at a time when Texas and other state legislatures are taking actions to restrict first-trimester medical abortions (in addition to banning all abortions after 20 weeks). Supporters of such legislation say that restricting medical abortions will protect women’s health and safety, but medical organizations and others have argued that limiting access to such abortions early in pregnancy not only places added burdens on women (and their physicians), but also threatens their health.

Surgical vs. medical abortions

Surgical abortions mechanically dilate a woman’s cervix, a procedure that can, in some cases, damage that organ in ways that prevent it from remaining closed throughout subsequent pregnancies.

Medical abortions use a combination of two hormones — typically misoprostol and mifepristone (RU-486) — to break down the lining of the uterus and soften and dilate the cervix. This procedure more closely mimics an actual birth and thus causes less physical trauma to the woman’s body.

Medical abortions became available around 1992, but the use of mifepristone, which induces labor by blocking the action of the hormone progesterone, was added to the procedure only in 2000. By 2008, medical abortions make up more than two-thirds of all abortions performed in Britain (up from 18 percent in 1992), but only one-fourth of those performed in the United States. Hormonal drugs, however, are now often used before surgical abortions to help prevent damage to the cervix.

A dramatic decrease

For the current study, researchers at the University of Cambridge analyzed data from large databases that included more than 730,000 first births by women in Scotland between 1980 and 2008. They found that women during the early 1980s who reported having had one or more abortion had a 30 percent higher rate of preterm births during subsequent pregnancies than women who had never had an abortion.

But that rate dropped steadily and dramatically during the following two decades. After medical abortions were introduced in Scotland in 1992, the increased risk of preterm births dropped to 10 to 20 percent. And starting in 2001, after mifepristone became used in medical abortions, Scottish women who had an abortion were no longer more likely to give birth prematurely during later pregnancies than women who had never had an abortion.

The authors note that the study doesn’t prove that the two trends were related, “however, we speculate that modernising abortion methods may be an effective long-term strategy to reduce global rates of preterm birth.”

Preterm births are a major health concern here in the United States as well as elsewhere in the world. Nearly 500,000 babies — or one out of every nine — are born prematurely each year in this country, according to the U.S. Centers for Disease Control and Prevention. Medical issues related to preterm birth are responsible for 35 percent of all infant deaths, are the leading cause of long-term neurological disabilities in children, and cost the U.S. heathcare system more than $26 billion annually, the CDC also reports.

The study was published online Tuesday in the open-access journal PLoS Medicine, where it can be read in full.

Comments (1)

  1. Submitted by Ray Schoch on 07/11/2013 - 10:13 am.

    This is

    …merely science, and will have no effect on those opposed to abortion, whose arguments are largely based on religion and/or emotion. The notion that restricting or eliminating abortions will somehow “protect the health of the mother” by making future premature births less likely is fairly straightforwardly disproved by the study, but we can expect to see counter arguments to the effect that the sample was skewed in some fashion, the authors don’t know how to count, there are too many typographical errors, or something — anything — else.

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