Contraceptive or Abortifacient?

Birth control pills are routinely described as "contraceptives", that is, things that prevent conception, the beginning of a new human life. But in fact birth control pills sometimes act as "abortifacients", things that cause abortion.

Birth control pills act in three basic ways: (This information can be obtained from any standard reference work, such as the Physician's Desk Reference.)

They suppress ovulation, that is, they prevent the woman's body from releasing an egg.
They thicken the woman's cervical mucus, which makes it more difficult for sperm to reach the egg.
They alter the lining of the uterus so that the zygote (fertilized egg, the first stage in the life of a human being) cannot implant. The developing baby receives his oxygen and nutrition through the uterus, so if the zygote-baby cannot implant, he starves to death. This is, therefore, an abortion.

There are basically three types of birth control pills:

high-dose, progestin and estrogen;
low-dose, about half as much progestin and estrogen; and
mini-pill, small amount of progestin, no estrogen.

The early high-dose birth control pills acted primarily by suppressing ovulation. Studies found that these pills succeeded in preventing ovulation somewhere between 90 and 98% of the time. However, since October 1988 high-estrogen pills are no longer available in the United States. They were removed from the market because of various dangerous side effects.

The newer low-dose pills are less effective at preventing ovulation and therefore rely more on the remaining two methods. As an egg is microscopic, it can be difficult to tell in any given case whether an egg really has been released. But Dutch gynecologist Dr Nine Van der Vange made an extensive study of women using these pills. She found proof that an egg had been released in 4% of the cases, and found follicle growth typical of what one finds in early pregnancy in at least 52% of cases.

The workings of the mini-pill are not fully understood, but it appears to allow ovulation at least 40% of the time, according to Emory University's Contraceptive Technology.

So how often do birth control pills really cause abortions rather than prevent conception? Medical researchers simply don't know. Suppose it is as little as 1% of the time. As a woman ovulates about once a month, then in a year of regular sex using the pill for "protection" there would be just under 12 x 1% = 12% chance that she would have aborted a child this way.*. In five years the probability is a little under 5 x 12 x 1% = 60% -- the actual probability is 55% -- of at least one abortion. That small probability adds up over many months of use.

Some people have moral objections to contraception in principle. But that is not the issue here. Even those who see no moral distinction between preventing pregnancy through contraception and preventing pregnancy through abstinence, must still object to any birth control method that relies, even a small percentage of the time, on destroying a life that has already begun.

I recently heard the interesting rebuttal that, as birth control pills usually act by contraception, that any abortions that result should be accepted as an unfortunate accident. This is a little like saying that it's all right to fire a gun randomly in the dark, as you usually won't hit anybody, and in the few cases when you do, it should be accepted as an unfortunate accident.

* The biology in this article is probably involved enough without going into a long discussion of probability. Suffice it to say that 1% chance times 100 tries does not equal 100% chance of "success".

Posted 5 Sep 2000.

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