This belief is simply FALSE. It is not consistent with the research, leading to the unrecognized loss (death!) of babies. These hormones do not always prevent ovulation, but do always thin the endometrium of the uterus to some degree, making implantation of the fertilized egg more difficult, and therefore causing an unknown percentage of spontaneous abortions before the mother even knows she is pregnant.
I refer you to one of the most comprehensive and well documented studies I am aware of: Postfertilization Effects of Oral Contraceptives and Their Relationship to Informed Consent. And here is a personal note by the author of that study:
I have prescribed “the Pill” since 1978. My wife and I used the Pill for years, having no moral concerns about it. Then, in 1995 my friend and practice partner John Hartman, MD, showed me a patient information brochure — given to him by a friend — that claimed the Pill had a postfertilization effect causing “ . . . the unrecognized loss of preborn children.” John asked me if I had ever heard of such a thing. I had not. I did read the brochure and its claims seemed to be outlandish, excessive, and inaccurate. So, I decided to begin a literature search to disprove these claims to my partner, myself, and any patients who might ask about it. The more research I did, the more concerned I became about my findings. I called researchers around the country and interviewed them. During this process I met Joe Stanford, MD. Joe volunteered to assist in the research that ultimately became this systematic review. We were concerned enough about our findings and about the fact that so many of our colleagues and patients seemed to share our ignorance about this potential effect that we presented the preliminary results of our research at a number of research forums, just to see if we were off base. Most of the reviewers suggested that, although this evidence was new to them (as it was to us), it seemed accurate and not off target. Furthermore, several said that they thought it would change the way family physicians informed their patients about the Pill and its potential effects.
The most difficult part of this research was deciding how to apply it to my practice. I discussed it with my partners, my patients, ethicists I know and respect, and pastors in my community. I studied the ethical principle of double effect and discussed the issue with religious physicians of several faiths. Finally, after many months of debate and prayer, I decided in 1998 to no longer prescribe the Pill. As a family physician, my career has been committed to family care from conception to death. Since the evidence indicated to me that the Pill could have a postfertilization effect, I felt I could no longer, in good conscience, prescribe it — especially since viable alternatives are available. The support and encouragement that my partners, staff, and patients have given me has been unexpectedly affirming. It seems that my patients have appreciated the information I have given them. Many have been surprised or even shocked (as I was) to learn about this potential effect. Many of my patients have chosen to continue taking the Pill, and we have physicians in our practice and community who will prescribe it for them. Patients who take the Pill tell me that they are much more careful with their compliance. Others have chosen other birth control options — especially one of the modern methods of natural family planning. So, this is research that has changed my soul and my practice. It has been an extraordinarily difficult issue with which I have had to wrestle. I suspect it will be so for many who thoughtfully read and consider the evidence contained in this review.
Walter L. Larimore, MD