Since this thread now seems to be a clearinghouse for birth control stuff, I should add some things.
Pills are %99 effective (as effective as it gets).
Not to nitpick, but since this is an important topic, I need to point out that there are several inaccuracies here.
First of all, pills are
not 99% effective — at least not necessarily. The CDC lists them in
this chart as being 91% effective (100% - 9% = 91%,
although this is only an approximation because it doesnʼt necessarily consider the women who would not have gotten pregnant in a year even without any method).
They are also
not the most effective method by a long shot; per the above chart, theyʼre not even in the highest effectiveness
class.
Also, keep in mind that probabilities are not limited to integer percentages. Itʼs not just 99% or 100% — there is an infinite
and remarkably significant continuum between those two seemingly close numbers. 99% means that the odds of failure are 1 in 100. By contrast, 99.5% means that the odds of failure are 1 in 200, while 99.9% means that the odds are 1 in 1,000, and 99.99% means the odds are only 1 in 10,000 —
huge differences here!
As for birth control methods, the best one listed on that chart linked above is an implant, at 99.95% effectiveness. Thatʼs a 1 in 2,000 risk of failure, versus the chances with pills, which are just under 1 in 11. With that said, some of that difference probably boils down to these most probably being
typical use figures. Typical and ideal use will be much closer for the implant than for pills, because thereʼs not much to be able to screw up once itʼs installed. The
ideal use (i.e., closely monitored clinical trial) effectiveness of oral contraceptives is probably a little closer to, but still not as high as, some of the other methods such as implants and IUDs.
Iʼve gone into birth control in quite a bit of detail in
this post.
Topics Iʼve covered there at least somewhat include:
- Sex makes babies, period. Especially for seducers. Numerically, all non‑surgical methods we have unilateral access to for casual scenarios do carry a pregnancy risk that is far from remote.
- Your method(s) of choice might depend on how youʼd feel about accidentally knocking up the particular girl in question. Certainly true for me.
- Condoms actually arenʼt as bullet-proof a method as people think.
- A much-overlooked birth control method that can be very useful for those who want to venture going raw in casual encounters: contraceptive sponges. Short story is, not quite as effective as some other methods, but much better than nothing, and quite good when combined with pull‑out.
- Probabilities of knocking up a girl from a single act. Failure rates are normally always expressed in terms of pregnancies per 100 couple‑years, which isnʼt always so helpful, so I built a fertility simulator to investigate different scenarios including single acts.
- Failure rates have only been studied for monogamous couples and are not necessarily reflective of the risks to a man who is having sex with multiple women — this has to do with ovulation timing. I went into a lot more detail in a draft post I never finished, but I do have some interim simulation results in the above‑linked post.
- Some interim simulation results for various combinations of birth control. (There are some “gotchas” related to computing probabilities for combinations of methods, which I discussed more in an unfinished draft, but did consider in the numbers given in the above‑linked post.)
- There are other significant limitations to the accuracy of reported failure rates that can at worst make comparisons between different methods practically worthless.
- “Typical use” as stated in studies can be remarkably lax.
See the post for much more details.
Regarding calendar-based methods, please note that there are significant physiological variations in the timings of the follicular and luteal phases, and those methods generally rely on population means. As such, they could fail catastrophically for some subset of the population of women. Thus the rather high failure rate, 24%, given in the CDC chart linked above. However, when combined with other methods it can be reasonable.
And if youʼre
really adventurous, thereʼs a company working on
a switch you can have installed into your nutsack to turn your swimmers on and off. Iʼm not even joking:
https://bimek.com/
It should have basically the same effectiveness as a vasectomy, but you can reverse it on your own by feeling around for it and pushing the safety button while flipping the switch. However, they do cut the vas deferens to install it into the switch, so if anything goes wrong or you want the switches removed (itʼs actually a pair, of course), then you would become permanently sterile. I want a child enough that I wonʼt even consider it until I have my half‑South‑Sudanese kid, but it could be more of interest to a parent who doesnʼt
think he wants more but isnʼt certain.