Friday, October 10, 2008

Contraception Effectiveness

Some methods of contraception are pretty good and some just suck. Here's a list of a few from worst to best...
(stats taken from Toronto Notes 2008. For more details about each method, go here)

Chance
- nothing used...just flying by the seat of your pants and rolling a 10-sided dice every time = 10.0%

Female condom = 75.0%
Withdrawal method/coitus interruptus = 77.0%
Rhythm method/calendar/mucous/symptothermal = 76.0%
Spermicide along = 82.0%
Diaphragm w/ spermicide = 90.0%
Condom alone = 90.0% (assuming proper use which often doesn't happen)
Condom w/ spermicide = 95.0%
NuvaRing (once-a-month hormonal contraceptive) = 98%
Depo-Provera = 99%
Hormonal skin patch > 99%
Oral Contraceptive Pill = 98.0-99.5% (depends on compliance)
Tubal ligation = 99.6%
Vasectomy = 99.8%
Abstinence = 100.0%

What I don't understand is how the surgical methods (tubal ligation and vasectomy) aren't 100%? If you tie off the tubes and do a little snip-snip, how can the sperm still get there and induce a pregnancy 0.2-0.4% of the time? Another category I didn't include are the emergency postcoital contraceptive (EPC) methods, also referred to as the "morning-after pill". By taking a large bolus of progestin or combo estrogen/progestin after the fact within 24 hrs, they will terminate any potential pregnancy 98% of the time (you can take it up to 72 hrs after I think). I wouldn't say they prevent a pregnancy because technically fertilization may have taken place in the uterine tubes at that point - they just do a very good job at making sure it doesn't progress any further. I think there are some serious ethical implications of EPC methods that separate it from the other classes of contraception.

If you don't want to be starting a family anytime soon, maybe it's time to consider how effective your chosen method of contraception is and make changes as necessary...

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4 Comments:

Blogger Meera said...

Cool, Matt! Do you have stats on all of the above in regards to STI prevention also? Just cuz I'd almost rather get pregnant than get HIV or cervical cancer or a lifetime of genital warts.

Also, percentages are all well and good until you're the 1 in 10 who used the condom correctly but got pregnant anyways. Yikes.

10:19 AM  
Blogger Matt said...

Hey Meera!

I haven't found any stats for STI prevention but if I come across some I will definitely pass it on.

11:17 PM  
Blogger 44darts said...

don't ask me about the mechanism behind it but from what i know, in some cases the fallopian tubes in tubal ligation or the ductus deferens in a vasectomy can actually reconnect. seriously. it's like it's got a mind of it's own! that's scary man.

11:28 PM  
Blogger Meera said...

Ya that's what we learned too, it just grows back on it's own sometimes. Creepy.

7:45 PM  

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