5 ms·

>How the numbers were calculated: The probability that a woman doesn't get pregnant at all over a given period of time is equal to the success rate of her contr

by adsjfk 12y ago

>How the numbers were calculated: The probability that a woman doesn't get pregnant at all over a given period of time is equal to the success rate of her contraceptive method, raised to the power of the number of years she uses that method. This does assume that the chance of getting pregnant after a year is independent of the person/people using it, though... presumably there are reasons other than a random roll of the dice why various birth control methods fail, which could well affect the distribution. (It also seems absolutely crazy to give these statistics "per year" when I'd feel pretty confident in saying that it depends on how often you have sex!)

eurleif 12y ago
Well, there are separate numbers for "perfect use" versus "typical use". Presumably, perfect use is independent of the person using it.
- adsjfk 12y ago
  Example: I'd guess that when hormonal birth control fails despite being used perfectly, it could well be related to the person's particular biology. So if it failed for them one year, there'd be a high chance of it failing the next. And if it worked for the previous year, there's a lower chance of whatever goes wrong going wrong. (I'd be curious to hear from someone who knows what they're talking about, though!)
  - pstrateman 12y ago
    The perfect use line for "Pill, Evra patch, NuvaRing" virtually matches that of "Hormonal implant" The key difference is the typical use lines are wildly different. (I thought it was interesting that Hormonal implant was more effective than male sterilization.)
- cperciva 12y ago
  Perfect use means "the user did not make any mistakes". A woman who gets pregnant after forgetting to take the pill one day is a "typical use" birth control failure; a woman who becomes pregnant because her natural hormone levels are such that the birth control pill (consistently taken at the same time every day) doesn't render her infertile is a "perfect use" birth control failure. Similarly, couples who intend to use condoms but occasionally forget (or get carried away etc.) would be "typical use", but a man with a cat-like barbed penis which makes holes in condoms could still qualify as "perfect use".
  - SilasX 12y ago
    That always struck me as strange, to "not using it" as using it. It's like the reverse of the tactic of saying that the fried chicken is healthy if you don't eat the skin.
    - cperciva 12y ago
      I believe the medical community refers to this as "patient non-compliance". It's an important factor for doctors to consider; it often makes sense to prescribe a "worse" medication if the "more effective" medicine has side effects which often cause patients to stop early or to skip or forget doses. New formulations of drugs are often advertised to doctors as being just as effective as previous versions but with "improved patient compliance" due to easier dosing schedules (e.g., daily instead of every 8 hours) or fewer side effects.
  - mjevans 12y ago
    In response to the question of 'typical use', I think that it also depends on the context of birth control. There are types of birth control which are somewhat passive; they are renewed at a pre-defined interval which is not related to intercourse. Therefore, considering other types which are only necessary to be applied during the window of intercourse, 'normal use' might reasonably include times where that was the /plan/ but for which the users 'forgot'.
  - baddox 12y ago
    There's a comment worth reading all the way to the end.
    - cperciva 12y ago
      I like to think that all of my comments are worth reading to the end!
      - baddox 12y ago
        I'll skip right to the end from now on, to know what I'll be getting myself into.
beachstartup 12y ago
i imagine the reason you're using a throwaway account (created 53 minutes ago, the same time as your comment as of my reading it) and guarding your words carefully is because you're tiptoeing around the fact that.... sometimes women lie about taking birth control in order to get pregnant 'accidentally on purpose'. men and women both do terrible things; this is one of the things women do.
- jakobegger 12y ago
  I strongly doubt that's what was meant. Contraceptives require a lot of discipline to be used correctly. Did you accidentally try putting a condom on the wrong way? Don't turn it around, throw it away. Did you have diarrhea after taking the pill? No sex this month. The effectiveness of a contraceptive depends a lot on the discipline (and personality) of the people using them. Many people don't even read the instructions that come with the contraceptives. That's why they are ineffective, not because partners lie to another about using contraceptives.
  - debaserab2 12y ago
    Yep, and on top of that they may be ineffective when combined with other medicine such as antibiotics. With the way antibiotics are handed out in the US, it's not a given that this fact is made clear to patients that could be effected.
  - beachstartup 12y ago
    > That's why they are ineffective, not because partners lie to another about using contraceptives. sorry, i just don't agree. you seem to entirely discount deception and coercion, which are the female and male forms of the same kind of birth control 'failures' that people tend to lie about on surveys.
    - anon4 12y ago
      The good part is that the deception is already baked-in into the final statistics. Basically it tells you "if the woman you're sleeping with is on the pill, you have this much chance of having an unexpected child". So wear a condom and start getting paranoid when she asks that you have sex without one. disclaimer: I am not a sex expert

by adsjfk 12y ago

eurleif 12y ago

Well, there are separate numbers for "perfect use" versus "typical use". Presumably, perfect use is independent of the person using it.

adsjfk 12y ago
Example: I'd guess that when hormonal birth control fails despite being used perfectly, it could well be related to the person's particular biology. So if it failed for them one year, there'd be a high chance of it failing the next. And if it worked for the previous year, there's a lower chance of whatever goes wrong going wrong. (I'd be curious to hear from someone who knows what they're talking about, though!)
- pstrateman 12y ago
  The perfect use line for "Pill, Evra patch, NuvaRing" virtually matches that of "Hormonal implant" The key difference is the typical use lines are wildly different. (I thought it was interesting that Hormonal implant was more effective than male sterilization.)
cperciva 12y ago
Perfect use means "the user did not make any mistakes". A woman who gets pregnant after forgetting to take the pill one day is a "typical use" birth control failure; a woman who becomes pregnant because her natural hormone levels are such that the birth control pill (consistently taken at the same time every day) doesn't render her infertile is a "perfect use" birth control failure. Similarly, couples who intend to use condoms but occasionally forget (or get carried away etc.) would be "typical use", but a man with a cat-like barbed penis which makes holes in condoms could still qualify as "perfect use".
- SilasX 12y ago
  That always struck me as strange, to "not using it" as using it. It's like the reverse of the tactic of saying that the fried chicken is healthy if you don't eat the skin.
  - cperciva 12y ago
    I believe the medical community refers to this as "patient non-compliance". It's an important factor for doctors to consider; it often makes sense to prescribe a "worse" medication if the "more effective" medicine has side effects which often cause patients to stop early or to skip or forget doses. New formulations of drugs are often advertised to doctors as being just as effective as previous versions but with "improved patient compliance" due to easier dosing schedules (e.g., daily instead of every 8 hours) or fewer side effects.
- mjevans 12y ago
  In response to the question of 'typical use', I think that it also depends on the context of birth control. There are types of birth control which are somewhat passive; they are renewed at a pre-defined interval which is not related to intercourse. Therefore, considering other types which are only necessary to be applied during the window of intercourse, 'normal use' might reasonably include times where that was the /plan/ but for which the users 'forgot'.
- baddox 12y ago
  There's a comment worth reading all the way to the end.
  - cperciva 12y ago
    I like to think that all of my comments are worth reading to the end!
    - baddox 12y ago
      I'll skip right to the end from now on, to know what I'll be getting myself into.

beachstartup 12y ago

i imagine the reason you're using a throwaway account (created 53 minutes ago, the same time as your comment as of my reading it) and guarding your words carefully is because you're tiptoeing around the fact that.... sometimes women lie about taking birth control in order to get pregnant 'accidentally on purpose'. men and women both do terrible things; this is one of the things women do.

jakobegger 12y ago
I strongly doubt that's what was meant. Contraceptives require a lot of discipline to be used correctly. Did you accidentally try putting a condom on the wrong way? Don't turn it around, throw it away. Did you have diarrhea after taking the pill? No sex this month. The effectiveness of a contraceptive depends a lot on the discipline (and personality) of the people using them. Many people don't even read the instructions that come with the contraceptives. That's why they are ineffective, not because partners lie to another about using contraceptives.
- debaserab2 12y ago
  Yep, and on top of that they may be ineffective when combined with other medicine such as antibiotics. With the way antibiotics are handed out in the US, it's not a given that this fact is made clear to patients that could be effected.
- beachstartup 12y ago
  > That's why they are ineffective, not because partners lie to another about using contraceptives. sorry, i just don't agree. you seem to entirely discount deception and coercion, which are the female and male forms of the same kind of birth control 'failures' that people tend to lie about on surveys.
  - anon4 12y ago
    The good part is that the deception is already baked-in into the final statistics. Basically it tells you "if the woman you're sleeping with is on the pill, you have this much chance of having an unexpected child". So wear a condom and start getting paranoid when she asks that you have sex without one. disclaimer: I am not a sex expert