If you use either a pill or condom to have sex with your partner, what is the probability of getting pregnant and/or getting a venereal dicease in each case?

I wonder which is more effective in terms of the probability.

Is there any research or statistics in this field? I don't mind it by country and age (though it is preferable to filter it), but I would like to restrict it only to heterosexual sex.

  • Decease is death. You do know the pill has no effect on venereal disease?
    – paparazzo
    Commented Mar 30, 2017 at 16:13
  • @Paparazzi Oh my English sucks. It's disease. But does it have literally NO effect on venereal diseases?
    – Blaszard
    Commented Mar 30, 2017 at 16:20
  • @Blaszard No effect whatsoever on venereal disease. Birth control pills prevent only pregnancies, not diseases.
    – Carey Gregory
    Commented Mar 31, 2017 at 0:34

1 Answer 1



The pill slightly more effective than condom for contraception. Other methods are better still.

The pill is ineffective for preventing STI; condoms are mostly effective.

In Full

First things first. Statistics on contraception efficacy are widely available, so as a bonus you are getting info on several more types than just 'condom' and 'pill'.

How effective is contraception at preventing pregnancy?

Reported in percentages; take the percent away from 100 if you would prefer to know how many women in a hundred will fall pregnant despite using the contraception correctly.


  • male condoms: 98% (NB heavily dependent on effective / proper use)
  • female condoms: 95%
  • diaphragms: 92-96%
  • caps: 92-96%
  • COCP (combined oral contraceptive pill): >99%
  • POP (progestogen-only pill): 99%

Long-active Reversible Contraception (LARC)

  • contraceptive injection: >99%
  • contraceptive implant: >99% (NB: over three years)
  • IUS (intrauterine system): >99% (NB: over five years)
  • IUD (intrauterine device): >99%
  • contraceptive patch: >99%
  • vaginal ring: >99%


  • female sterilisation: >99% (1 in 200)
  • male sterilisation: > 99% (1 in 2000)


  • natural family planning: ≤ 99% (ie up to 99%, depending on how closely it is followed)

(condoms and pills highlighted in bold)

Source: NHS contraception guide; from which the stats are liberally taken.

Note: The CDC also publishes a poster family planning methods. The percentages are the number of pregnancies per year (ie the opposite of the NHS published statistics). They also give actual effectiveness, rather than assuming correct use every time. For condoms in particular, this means only 82% effectiveness (vs 99%); and for the pill, 92% (vs >99%). There is further information available.

Although it isn't an 'accepted' source, there is a Wikipedia page with a table on contraceptive effectiveness; the more important part is in the references section of the article which has plenty of further reading.

How effective are condoms vs the pill for preventing STIs?

STIs need a method of entry to pass an infection from one host to another. Condoms, when used correctly, form a physical barrier preventing entry. The pill gives no barrier to entry.

I have yet to find a (reputable) source which claims that the pill gives any protection for STIs.

On the other hand, the CDC by itself has several resources on condom effectiveness at preventing STIS:

  • 1
    Good answer but not sure why you said you can't find a source claiming the pill protects against STIs. That's like saying you can't find a source claiming left is right or night is day. Just saying it that way implies it could be true, which is very misleading to someone who thinks it's possible.
    – Carey Gregory
    Commented Mar 31, 2017 at 0:39
  • @CareyGregory I take your point. I guess my thinking was: if I said "it gives no barrier" and left it at that it's an unreferenced assertion; by saying there are no sources to back it up makes it clear I have looked for references-- basically, "it's not just me saying this"! If you have a better way of phrasing it I am open to suggestions :)
    – bertieb
    Commented Mar 31, 2017 at 6:27
  • (I also think in play here is me not wanting to dismiss something out-of-hand; there could be some really subtle effect on uterine secretions, membrane integrity or something that gives a 0.1%/0.5%/1%/etc 'protection'. Scientist at heart!)
    – bertieb
    Commented Mar 31, 2017 at 6:29
  • Sorry for my ignorance but what is the "short-acting" and "long-active"?
    – Blaszard
    Commented Apr 1, 2017 at 17:25
  • @Blaszard - Long-active and short-acting contraception Commented Apr 1, 2017 at 21:48

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