# Why don't female immune systems reject sperm?

**URL:** <https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055>\
**Category:** Factual Questions\
**Created:** [May 16, 2012, 2:43am UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055 "2012-05-16T02:43:32Z")\
**Posts on this page:** 5\
**Page:** 2

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**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\
**Post date:** [May 16, 2012, 9:00pm UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055/21 "2012-05-16T21:00:33Z")

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> [@WhyNot](#):
>
> …which is why women aren’t constantly full of dead sperm…

I was gonna go with “gravity.”

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**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\
**Post date:** [May 16, 2012, 10:31pm UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055/22 "2012-05-16T22:31:09Z")

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> [@purplehorseshoe](#):
>
> I was gonna go with “gravity.”

Gravity and fluids probably explain the flushing of the bulk of the semen in the vagina and uterus, but there are hundreds of dead sperm and bits of dead sperm in the fallopian tubes and even inside the abdomen, if they live to swim so far.

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**Author:** ![I\_Know\_Nothing](https://avatars.discourse-cdn.com/v4/letter/i/f04885/32.png) [@I\_Know\_Nothing](https://boards.straightdope.com/u/I_Know_Nothing)\
**Post date:** [May 16, 2012, 11:19pm UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055/23 "2012-05-16T23:19:02Z")

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I believe the female immune response in this instance is mostly a premptive one. Instead of fighting off sperm in the vagina, they frequently emply strategies to prevent it from entering in the first place, e.g. not returning phone calls, restraining orders, gossiping, panty hose, sweat pants, door locking, and Twilight movies. That’s how it seems to work for me anyway.

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**Author:** ![cynyc](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@cynyc](https://boards.straightdope.com/u/cynyc)\
**Post date:** [May 17, 2012, 2:05am UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055/24 "2012-05-17T02:05:10Z")

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Apologies if somebody got here already but look up corkscrew (alternative?) vaginas in ducks. Brilliant!

FWIW.

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**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\
**Post date:** [May 17, 2012, 3:50pm UTC](https://boards.straightdope.com/t/why-dont-female-immune-systems-reject-sperm/622055/25 "2012-05-17T15:50:36Z")

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> [@drachillix](#):
>
> Oh to experience the heat of battle 😃

Ready your lance, good sir, and CHARGE!

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