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Saturday, February 11, 2012

Myth Buster: Plan B is NOT an Abortion Pill!

I was catching up on the news headlines, and something struck me about the discussions surrounding the so-called "morning-after" pills including the brand name Plan B (there are a couple of other brands).  The commentators seemed to be telling us that these pills are the same as abortion-inducing pills like RU-486 (mifepristone).  This is a complete misrepresentation of the facts, so I felt the need to bust that myth.

The currently marketed formulations that are FDA-approved for use as emergency contraceptives contain only the hormone progesterone.  This is an important female hormone for regulation of the menstrual cycle, and it can inhibit/counteract the effects of estrogen.  Ovulation (the regular release of an egg from an ovary) depends upon a delicate balance between estrogen and progesterone during the month, and any disruption in that balance will inhibit the egg release and movement through the fallopian tube where it might meet sperm and be fertilized - i.e. conception.  This mechanism of action is significantly different from that of the abortion-inducing medication.

Mifepristone is an antagonist to progesterone, and it blocks the beneficial, pregnancy-preserving affects of that hormone.  It can disrupt an established pregnancy (one that has implanted on the uterine wall and is growing) simply by virtue of the fact that the developing pregnancy requires progesterone.  In contradistinction to that, the progesterone-containing "morning-after" pills cannot disrupt an established pregnancy and therefore cannot induce an abortion.

Emergency contraception is not a good substitute for regular use of any method of birth control because it is more unreliable at preventing the undesired pregnancy, and there may be more side-effects than standard birth control pills, patches, rings, injections, etc.  However, as a rescue method, and when taken within an optimal window of 72 hours following intercourse, these pills are an good option.  Women who are personally opposed to abortion need not fear that this is the way that these pills work.

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