More effective than the pill. Wait, what?

“Wait, what?” is my 13 year old son’s favorite line when something surprises him, and this definitely qualifies.

Let’s start with this:  if you look at the CDC resources for information on methods of family planning, you’ll see typical use effectiveness as follows (selected, expressed as failure rates):

• The combination pill:  9%.
• The minipill:  also 9%.
• The condom:  18%.
• Natural family planning or fertility awareness:  24%.

leaving NFP users stuck with explanations like, “well, that lumps in all types of NFP” and “well, they didn’t instruct and motivate women properly in their studies.”  And, indeed, these statistics — neither for the hormonal contraceptives nor for NFP — are without any sources/footnotes, which is understandable, perhaps, on the PDF factsheet version of this information, but should certainly be available somewhere on the site, and it’s not.  You’ll also notice that all methods of NFP/FAM are lumped in together as well.

But the WHO is a different story.

Here’s what they have to say on their equivalent table of modern contraceptive methods (note that WHO shows effectiveness rates, so I’m converting to failure rates here):

• The combination pill:  8%.
• The minipill:  3-10%.
• The condom:  15%.
• Standard Days Method:  12%
• BBT Method:  25%
• Two-Day Method:  14%
• Sympto-thermal Method:  2%.

And they cite references.  For the 2% rate, they cite “Manhart et al, 2013,” which is easily found on google:  “Fertility awareness-based methods of family planning:
A review of effectiveness for avoiding pregnancy using SORT.”  Now, this isn’t the study itself, but a review of mutliple studies, and the key study here is “The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple’s sexual behaviour during the fertile time: a prospective longitudinal study,” which is (woo-hoo!) available online for free.  And this is a major study, with 900 couples, so the effectiveness rate is statistically credible and not just a fluke.  This study was undertaken in Germany, where I have the understanding there are more couples interested in hormone-free methods of family planning, and there was a mix of couples who abstained during the fertile period and those who sometimes used barrier methods, without any impact on effectiveness.   But it’s also noteworthy that the study occurred in Germany, where the TFR of 1.4 is itself an indicator that Germans are in general very motivated to succeed in their family planning goals.

That the Standard Days Method and the Two-Day Method have lower effectiveness rates is not a surprise, because they are less effective methods.

But what about that 25% for the BBT method?  That’s generally a more conservative method so it’s surprising to have such a high reported failure rate.

The reference WHO gives here is “Trussell, 2009” which produces one result, “Cost Effectiveness of Contraceptives in the United States.”  And this article is actually focused on the math of the “cost effectiveness” of preventing pregnancies by looking at the cost of the methods themselves, their effectiveness, and the cost of the abortions or births due to pregnancies that occur.  Now, this is a mindset that assumes that every unintended birth is a net “extra” birth in this country, and that, without those unintended prengnacies, we’d never have those births — rather than what I’ve read as an operating assumption in other literature, that unplanned pregnancies are “mistimed” and without them, most women would still go on to have those children, just at a different time in her life.  But in any case, there is a table of effectiveness, and the 25% that the WHO references comes from this table, and is actually, again, as with the CDC, the lumping-together of all NFP/FA methods.  Perhaps it’s even the same source, and the 25% is just rounding.  What’s more, the reference for all these failure rates is a text, “Hatcher RA, Trussell J, Nelson AL, Cates W, Stewart FH, Kowal D. Contraceptive Technology, nineteenth revised edition. New York NY: Ardent Media; 2007,” which is not viewable online.  So the 25% failure rate is a dead-end; I’m simply not finding any references to any studies that establish this rate.  (Perhaps a reader will have more success?)  My guess is that this was some kind of retrospective study asking women, “what method did you use?” and labelling as NFP/FAM any response about “I just don’t have sex when I think I’m fertile,” rather than a controlled study of any kind based on a specific method and genuine instruction.  Bottom line:  I would discard the 25% as not credible.

So that’s what I’ve got for you for discussion today, for those of you who are exhausted by the protests and the cabinet pick rumors and all the other nonsense.  And, yes, I am aware that it sidesteps entirely the attempts among contraception advocates and policy-makers to move as many women as possible onto IUDs, which is a whole ‘nother story.

image:  https://commons.wikimedia.org/wiki/File%3AQuecksilber-Basalthermometer.jpg; By Gelegenheitsautor (Own work) [Public domain], via Wikimedia Commons