Catholic and pro-life medical researchers say that current scientific evidence fails to disprove that two leading emergency contraceptive pills are not abortifacients. 

morning after pill
New studies have created debate on what morning-after pills really do. Shutterstock

That position runs counter to recent statements from supporters of emergency contraception, including a New York Times story that cited studies and quoted scientific researchers, obstetricians-gynecologists and others to say that the moral debate over morning-after pills and abortion is “probably rooted in outdated or incorrect scientific guesses about how the pills work.” 

Not so, said Dr. Marie T. Hilliard, director of bioethics and public policy

at the National Catholic Bioethics Center in Philadelphia. 

The Times article is “incomplete and misleading at best,” Hilliard told Our Sunday Visitor. 

Dr. Donna Harrison, an OB-GYN and director of research and public policy for the American Association of Pro-Life Obstetricians and Gynecologists, also said the Times story convoluted facts, misquoted studies and lumped two very different drugs together. 

“I don’t think you can say there is a scientific consensus that these drugs do not have post-fertilization mechanisms,” Harrison said.

How the pills work

The question of whether emergency contraceptives such as Ella and Plan B One-Step — both are sometimes called the “morning-after pill” — work in part by preventing a fertilized egg from implanting on the uterine wall is an important issue for Catholics and others who believe life begins at conception. 

It is accepted that both Ella and Plan B are designed to prevent pregnancy by blocking ovulation and thickening cervical mucus to limit sperm mobility.  

The issue is whether the drugs’ active ingredients also affect the uterine wall by making it hostile to implantation. 

Some recent studies say that Plan B, which has levonorgestrel (LNG-EC) as its active ingredient, may not prevent an embryo from implanting, but some experts say that does not tell the whole story. 

In March, the International Federation of Gynecology and Obstetrics issued a joint statement with the International Consortium for Emergency Contraception that claimed studies definitively prove that LNG-EC pills cannot prevent implantation of a fertilized egg. Dr. Petra M. Casey, an OB-GYN at the Mayo Clinic, told The New York Times that emergency contraceptive pills “don’t act after fertilization.” 

However, Dr. Patrick J. Yeung, director of the St. Louis University Center for Endometriosis, told OSV that several studies on Plan B used flawed methodologies. 

“Plan B does thin the lining of the uterus,” said Yeung. He noted that the U.S. Food and Drug Administration has refused to remove the possibility of a post-fertilization effect from Plan B’s package label. 

Dr. Kathleen Raviele, an OB-GYN and former president of the Catholic Medical Association, said Plan B also has been shown not to always prevent sperm from penetrating the cervical mucus. 

Supporters of emergency contraception point to two recent studies that seem to support their theory that Plan B is not an abortifacient. 

In 2007, the Department of Obstetrics and Gynecology at the University of Sydney in Australia found that three of 17 women who had intercourse during their fertile cycles and took LNG-EC pills after ovulation still became pregnant, which the researchers suggested contradicted the theory that the pills worked after ovulation. 

A 2011 study by the Instituto Chileno de Medicina Reproductiva in Chile reported that eight of 45 women who had intercourse during their fertile days still became pregnant when they took an LNG-EC pill after ovulating. The study’s authors said those findings are incompatible with the inhibition of implantation by LNG-EC in women. 

But the same 2011 study also found that 62 of 87 women who took LNG-EC before ovulation still ovulated, but none of them became pregnant. “This clearly suggests a post-ovulation effect,” said Hilliard. She also said research has shown that LNG-EC’s restriction of sperm mobility does not act quickly enough to prevent sperm from reaching the fallopian tubes, which occurs within five minutes of intercourse. 

Plan B’s active ingredient is essentially a large dose of a progestin, a synthetic form of progesterone, which is a hormone in a woman’s body that allows an embryo to implant and for placental connections to grow. Harrison said Plan B will not cause an abortion after the embryo has already attached, but the question is what effect the higher dose of progesterone has on the uterine wall. Harrison said studies have shown it causes the endometrium to not be prepared for implantation.

An embryo destroyer

While some room remains for debate on Plan B’s post-fertilization effects, Catholic experts said there is no question about the abortifacient properties of Ella, which is chemically similar to RU-486, the so-called abortion pill that detaches an embryo from the endometrium. 

“The dog in the fight really is Ella. What the culture of death is trying to do is use the lack of clarity of data on Plan B, which has less evidence of embryocidal effect than Ella, to make people assume that this lack of clarity applies to all ‘emergency contraceptives.’ Plan B is the bait-and-switch when Ella is clearly embryocidal. Ella is the same kind of drug as RU-486,” Harrison said. 

Ella’s active ingredient, ulipristal, blocks progesterone in the ovaries and the endometrium, which destroys receptivity to embryonic implantation, Hilliard said. She pointed out that Ella is marketed to be used up to five days after intercourse. 

“Clearly, it has abortifacient properties,” Hilliard said. 

Erica V. Jefferson, a spokeswoman for the U.S. Food and Drug Administration, said “some data” suggests Ella does not inhibit implantation, she said less is known about that drug than Plan B. 

James Trussell, a Princeton University economics professor, and Kelly Cleland, a staff researcher in the Office of Population Research at Princeton and the executive director of the American Society for Emergency Contraception, co-wrote a June 15 article in Science Friday saying that there is some evidence that Ella produces changes in the uterine lining, “but whether these changes would impair the implantation of a fertilized egg is unknown,” they wrote. They said that emergency contraceptives effectively delay ovulation if taken at the right time during a woman’s cycle. 

Harrison said she attended an FDA Advisory Committee Hearing on Ella in 2010 at which data was presented that Ella is 95 percent effective at preventing a pregnancy. 

She said that prompted committee members to point out to the manufacturers that Ella’s effectiveness could not be explained solely by preventing ovulation. 

However, Trussell and Cleland wrote that if emergency contraceptive pills were effective at preventing implantation, then their failure rates would be even lower than what they are, though the authors acknowledged that LNG-EC only fail about 2.2 percent of the time, while ulipristal acetate’s failure rate is around 1.4 percent. 

Harrison noted that Trussell has at times claimed an efficacy rate for Plan B of more than 90 percent, and at other times saying it is around 50 percent. When the post-fertilization method is debated, the 50 percent rate is mentioned, but when funding is the issue, Harrison said Trussell and like-minded researchers use Plan B’s higher success rate. 

“The other side keeps changing the numbers,” she said.

Brian Fraga writes from Texas

This article has been revised to reflect the following correction:

Correction, July 5, 2012: An earlier version of this article said Plan B contains a large dose of progesterone, a natural hormone. Instead, Plan B contains a progestin, a synthetic version of the hormone.