# Which contraceptive methods prevent fertilization entirely, and not just pregnancy? **URL:** \ **Category:** Factual Questions\ **Created:** [April 15, 2019, 9:28pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594 "2019-04-15T21:28:40Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [April 16, 2019, 9:05pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/21 "2019-04-16T21:05:34Z")
> [@Slash1972](#): > > I guess. But it seems like the same thing can be said about oral sex: > > “Can I get pregnant from giving oral sex?” > > “Yes, if the man withdraws from your mouth and ejaculates on your vagina” Well, true, though the vagina is considerably closer to the anus than the mouth is. Also, never underestimate how clumsy or inaccurate a sexually-aroused person in a darkened room can be. Possibly urban legend, but Dr. Ruth Westheimer, when asked how many sperm it took to cause a pregnancy, allegedly said, “just one quick one.” ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [April 17, 2019, 3:07am UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/22 "2019-04-17T03:07:03Z")
I would prefer methods in which user error isn’t a factor. The most a appealing are hormonal IUDs, copper IUDs, and a Nexplanon implant. Depo shots are also an option but I’d prefer something removable in case of adverse effect from hormonal BC. I tried reading some technical papers about these methods but I’m not sure I fully understand them. They also make it sound like we don’t really know what percentage of times the BC prevented fertilization rather than preventing implantation. I assumed copper was the best because it stopped sperm. But some of what I saw also suggests it ( rarely ) also stops implantation. Which then makes me wonder - are hormonal methods more effective at preventing fertilization because they often prevent ovulation and egg availability whereas copper does not? Or is copper so much better at stopping sperm that it doesn’t matter if ovulation occurs? I haven’t found anything yet that conclusively answers this question. Between a copper IUD, hormonal IUD, or Nexplanon implant, which is most likely to prevent fertilization? Separate question: do hormonal IUDs have fewer side effects than birth control pills since they’re delivered to the right area more specifically and presumably require a smaller dosage? ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [April 17, 2019, 3:14am UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/23 "2019-04-17T03:14:35Z")
[The mode of action of IUDs - PubMed](https://www.ncbi.nlm.nih.gov/m/pubmed/3311625/) it’s a study that seems to address this question although it’s 30 years old and I’m not sure I fully understand the conclusion. ---
**Author:** ![Dana\_Scully](https://avatars.discourse-cdn.com/v4/letter/d/5daacb/32.png) [@Dana\_Scully](https://boards.straightdope.com/u/Dana_Scully)\ **Post date:** [April 17, 2019, 3:04pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/24 "2019-04-17T15:04:40Z")
> [@Tim\_T-Bonham.net](#): > > I would strongly urge you to have a licensed medical doctor do this! 😃 I was thinking the same thing. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [April 17, 2019, 3:34pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/25 "2019-04-17T15:34:09Z")
> [@](#): > > Vasectomy: This is probably the ideal option, since it’s something I can do myself and not ask my partner to do. It’s reliable and requires no effort once it’s done. However, it’s permanent. I’m very likely at peace with its permanent nature, but I’m kind of going through a weird transition period in my life right now, and I’m not quite 100% sure about that, so I hesitate to jump right to that option. > > Related: I know you can pay a service to freeze your sperm for IVF in the event that you want to use it later to conceive. And that vasectomy reversal is effective in some cases. But… if the testes are still producing sperm, they’re just cut off from the seminal fluid, why can’t we go retrieve sperm from inside the testes, or the surrounding tubing for IVF? At least what I’ve read hasn’t mentioned this as an option. As I mentioned to a friend of mine whose wife was regretting his vasectomy choice - “not to worry, they can harvest sperm. All they have to do is stick a big, long needle into your testes.” ☹ Birth control pills do allegedly prevent ovulation form happening at all. Of course, like all fire-and-forget mechanisms, nothing is 100%. Condoms leak, IUD’s pop out, pills don’t work 100% sometimes, foams and creams get sloshed out, diaphragms shift, the doctor “misses” or the tubes grow back together after a vasectomy or tubal ligation, etc. The only thing guaranteed 100% is either abstinence, menopause, or removal of the ovaries or testes - ie. the bits don’t do what they should. ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [April 17, 2019, 4:13pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/26 "2019-04-17T16:13:26Z")
> [@kenobi\_65](#): > > Possibly urban legend, but Dr. Ruth Westheimer, when asked how many sperm it took to cause a pregnancy, allegedly said, “just one quick one.” Isn’t she the one who said that if you’re using the rhythm method, the time to have sex was at the mid-point between periods? ---
**Author:** ![Mirtha](https://avatars.discourse-cdn.com/v4/letter/m/67e7ee/32.png) [@Mirtha](https://boards.straightdope.com/u/Mirtha)\ **Post date:** [May 14, 2019, 6:03pm UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/27 "2019-05-14T18:03:45Z")
With sperm, it’s a group effort - the first ones out of the gate break the enzymatic lining of the egg, lose energy to continue so they cannot impregnate, but if there’s more sperms swimming in the back, one of them will find the eroded area of the egg and get in. This is why a high sperm count is helpful in impregnating someone. It’s helpful to know also, the little fellas can live up to five days. A careless man would indulge five days prior to someone’s ovulation and ovulation is not really certain all the time. This is why people using the rhythm method for birth control are called parents. With all of the certainty we know about sperm, snipping vas deferans is the way to go. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [May 15, 2019, 1:49am UTC](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594/28 "2019-05-15T01:49:11Z")
> [@SenorBeef](#): > > Which then makes me wonder - are hormonal methods more effective at preventing fertilization because they often prevent ovulation and egg availability whereas copper does not? Or is copper so much better at stopping sperm that it doesn’t matter if ovulation occurs? I haven’t found anything yet that conclusively answers this question. I don’t know the answer to any of your questions, but I wanted to make it even more complicated 🙂 Some contraceptives (I don’t remember which) work mostly by preventing implantation. Ovulation works, sperm swim, fertilisation works – and implantation fails. [Previous page](https://boards.straightdope.com/t/which-contraceptive-methods-prevent-fertilization-entirely-and-not-just-pregnancy/832594.md?page=1)