PZ on Plan B

PZ Myers has a great post explaining the mechanism for Plan B, the emergency contraceptive that is the pro-life bickering point du jour.

a spike in LH levels triggers ovulation and progesterone suppresses LH. Hmmm. This suggests an idea. If you wanted to prevent ovulation, how would you do it?

(Consider this a test. Imagine that Jeopardy jingle playing right now.)

Time’s up—I bet everyone came up with the right answer, though. Giving someone a large dose of progesterone would shut down LH production, so there would be no ovulation, so no egg would be released, and any sperm happening to be in the woman’s reproductive tract would find nothing to fertilize.

Myers argues that Plan B is like a condom for women. Just as men can prevent sperm from being released, so women can prevent the egg from being released. No egg, no pregnancy, no abortion. Therefore the only possible reason pro-lifers might want to regulate Plan B is to control women’s sexual behavior, not to prevent abortions. Read the whole post, though, for a great brush-up on what fewer and few kids are getting taught in health class these days.

The pro-life response to this argument is that the egg may have already been released when Plan B was taken, and so Plan B might prevent the now-fertilized egg from implanting in the uterus. Therefore they are saving babies, not just restricting women’s lives. Putting aside the fact that the fertilized egg is no more a “person” than the separate sperm and unfertilized egg, the problem with this argument is that there’s NO scientific evidence to support it. There’s exactly the same amount of evidence that drinking root beer might prevent implantation. Should we ban root beer? There actually is some evidence that breast-feeding prevents implantation. Should we ban breast-feeding?

Let’s go over the evidence about Plan B one more time. Take a look at this analysis of its effectiveness:

A double-blind, controlled clinical trial in 1,955 evaluable women compared the efficacy and safety of Plan B (one 0.75 mg tablet of levonorgestrel taken within 72 hours of intercourse, and one tablet taken 12 hours later) to the Yuzpe regimen (two tablets of 0.25 mg levonorgestrel and 0.05 mg ethinyl estradiol, taken within 72 hours of intercourse, and two tablets taken 12 hours later). Plan B was at least as effective as the Yuzpe regimen in preventing pregnancy. After a single act of intercourse, the expected pregnancy rate of 8% (with no contraception) was reduced to approximately 1% with Plan B. Thus, Plan B reduced the expected number of pregnancies by 89%.

The expected pregnancy rate is 8 percent, and Plan B reduces that rate to 1 percent. But 1 percent still get pregnant. Where do you think that 1 percent comes from? You guessed it — it comes from the eggs that were already released at the time the medication was taken. Plan B does not prevent implantation. So the pro-life community is arguing that we should ban Plan B, thus increasing the pregnancy rate of these women by 800 percent. How many of those women do you think will have abortions later in their terms? Based on sales estimates and its $19 cost, about a million women a year are prescribed Plan B in the U.S. That’s roughly 70,000 prevented pregnancies. Do pro-lifers really want these numbers added to the abortion statistics? Wouldn’t it be preferable to make it available over the counter and prevent even more abortions? Even as a pro-choice advocate, who doesn’t see any ethical problem with terminating a pregnancy, I’d rather see these women avoid an expensive surgical procedure by taking a convenient, readily available contraceptive. Wouldn’t you? If you thought abortion was the equivalent of murder, wouldn’t you want Plan B to be even more widely available?

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2 Responses to PZ on Plan B

  1. Mary says:

    Speaking for myself: yes.

  2. dave says:

    I was hoping you’d be on board, Mary — now we just need another 50 million or so like you!

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