# When both are used correctively and together, what is the effectiveness of the birth control pill and a diaphragm?

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Wikianswers

97% or greater effectiveness

The 97% figure is based on the Typical Use column from this wikipedia page, assuming that a condom does not negatively interact with a diaphragm and spermicide. This is, in almost all cases, a very reasonable assumption.

Math: Male condom, 15% fail rate. Diaphragm + spermicide, 16% fail rate. 1 - .15*.16 = .976, or 97.6%.

If perfect use is assumed, instead of typical use, the figure rises to 99.9% effectiveness. (1 - .02*.06 = .9988)