Talk:Pearl Index

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I changed the word 'safety' to 'effectiveness' because the Pearl Index evidently concerns itself only with how well unwanted pregnancies are avoided. Rating various methods for safety would involve measuring the number and severity of unhealthy side effects. Wesley

[edit] List of values

This article really needs a list of values for various methods. Those should also be added to the repective articles, as it has been in Oral contraceptive. --Apoc2400 01:18, 14 November 2005 (UTC)

[edit] Sexual activity

Maybe it is just me being stupid, but how come there is no mentioning of the relation to the amount of sexual activity the involved persons have? And in particular, how that correlate with the choice of method of birth control?

A special case of the above could also be the effect on the sexual lust that some methods have, which may indeed decrease the chance/risk of getting pregnant, but not really in the way you would normally want.

213.112.173.167 16:53, 17 June 2007 (UTC) —Preceding unsigned comment added by 213.112.173.167 (talk) 15:07, 17 June 2007

Pregnancy rates based on where a woman is in her menstrual cycle are discussed at fertility awareness. During the least fertile portions of the menstrual cycle, couples could go twice a day or more and have a less than 1% chance of pregnancy per year. On the most fertile day, a single act of intercourse results in pregnancy about 2/3 of the time. This is a huge variation in fertility. Combined with the fact that most women do not track their fertility signals, I believe that makes any "sex per year" stats completely useless for birth control purposes.

As far as hormonal contraception making women not have any sex at all (yes, abstinence is an effective method of birth control), see Combined oral contraceptive pill#Sexuality for Wikipedia's current coverage of this issue. Because it is specific to hormonal contraception, this possible side effect is covered on those pages, not on the general topic of "Pearl Index". Lyrl ^Talk _C 15:15, 17 June 2007 (UTC)

I can only agree to that, but my point was more that I think it could (would?) be valid criticism of the Pearl Index to state that the figures are potentially affected by such factors in a systematic way.

I suppose that there is (or may be) a correlation between the level of sexual activity and choice of birth control method. This can then pop up in the PI values as an indication that method A is better than method B, while in practice it is rather so that method B is better liked by those having an active sexual life. The other way aorund, the choice of birth control method may affect the sexual activity (not only in the case of hormonal methods), and hence affect the likelihood of pregnancy in a more indirect way. This would clearly cause very hard to interpret results. 213.112.173.167 17:30, 17 June 2007 (UTC)

You may be right. The correlation between contraceptive method and sexual activity is something that has to be examined in research. I also want to respond to the idea that a single act of unprotected intercourse on the most fertile day leads to pregnancy in 2/3 of the cases. That is not true. The available research shows it's only 10 to 24%.193.67.185.234 09:47, 22 June 2007 (UTC)

Random intercourse throughout the menstrual cycle results in pregnancy 10-24% of the time. Women monitoring their fertility signs and deliberately timing intercourse have much higher rates of pregnancy. See PMID 8401097 (probability of conception .667 from a single act of intercourse on Peak day from WHO study) and PMID 1479570 (76% pregnancy rate first cycle of fertility-focused intercourse). Lyrl ^Talk _C 02:25, 23 June 2007 (UTC)