A nuclear war kicked off between the Russians and NATO in 2029. Humans now live in an irradiated wasteland.

Mushroom cloud for illustration

In the particular region where my story is set, approximately 20 000 human beings survived. Here’s my question: when the first generation of WW III survivors go on to continue their species and have children, will they face any problems in doing so?

I’ve heard that radiation and nuclear fallout is extremely harmful to fertility. From this site's very own Valerio Pastore,

Furthermore and even worse, those few survivors would remain clustered and scattered in small tribal enclaves unable to contact each other on long distances (no technology and no animals to use for transportation or to carry messages). Withing these enclaves, many men and women would just be infertile due to radiation. Those who could give birth would generate misshapen monsters with a very short life expectancy, and those incredibly rare babies who could reach sexual maturity in relative good health should soon start inbreeding, thus giving birth to once again defective babies. Extinction of humankind

Is this true? And if so, what could be done?

  • $\begingroup$ "Nuclear is extremely harmful to fertility": (1) Nuclear what? Nuclear families, nuclear magnetic resonance? (2) Hiroshima has 1,200,000 inhabitants. Nagasaki has 400,000 inhabitants... (3) And anyway, a war between NATO and Russia, two northern powers, will have minimal impact on the southern hemisphere. $\endgroup$
    – AlexP
    Commented Jul 1, 2020 at 18:35
  • 3
    $\begingroup$ @AlexP Certainly the southern hemisphere hopes so. $\endgroup$
    – John O
    Commented Jul 1, 2020 at 19:14
  • $\begingroup$ @John O: My world takes place in the American Southwest $\endgroup$
    – DT Cooper
    Commented Jul 1, 2020 at 19:20
  • 2
    $\begingroup$ I was curious about the smoke trails in that image. They are smoke rockets launched before the blast, and used to track the progress of the invisible blast front which alters their appearance from a distance because of refraction by the compressed air of the front. Read more about them here: nuclearweaponarchive.org/Usa/Tests/SmokeTrails.html $\endgroup$
    – Willk
    Commented Jul 1, 2020 at 21:06

3 Answers 3


They will be fine.

First - survivors are survivors for a reason. Like they did not have the bad stuff happen to them that happened to all the people that died. So maybe the survivors were elsewhere when the serious radiation went down.

But nay; nay - all of them got radiated to some degree, let us say. Are their baby-having days done? No.

Fertility among female survivors of the atomic bombs of Hiroshima and Nagasaki. Am J Human Genet 1972 Nov; 24(6 Pt 1): 613–622.

enter image description here

If you got a lethal dose of radiation, you had changes in your gonads consistent with reduced fertility. Not that you would get a chance to find out. Pregnant women with high doses often lost their pregnancies...

holy moly what a horrible thing. Nuking pregnant women.

OK - world building! Persons who survived did not have reduced fertility according to radiation dose as one would think. Conclusion - fertility (or at least fertility of women) is pretty durable vs mutagens. I suspect males not so much - men who get chemo are routinely rendered azoospermic but it is not infrequent for women who get chemo to conceive and have normal babies.

In your world the men who can conceive children might be few and far between. It will probably be known who they are. These men might be in demand.


We're probably goners

It's difficult to determine non-experimentally (and good luck getting that grant funded), but there seems to be a loose consensus that the minimum viable population for humans is ~160. You could make a case for this number dropping a bit through careful lineage tracing and family planning, but it gives us an order of magnitude approximation.

This MVP is only 2 orders of magnitude away from our total population, so certain numbers in your question matter quite a bit. What fraction of children reach sexual maturity? How populous are these enclaves, how many of them are there, and are any of them reasonably close together (i.e, close enough for a reasonably-safe, one-way trip to allow a modicum of interbreeding)? If the fertility rate is <10% and there are more than 10 enclaves, humanity will have no choice but to try to come together

Without technology, communication will be difficult. Smoke signals and clearly-marked trails will be the best way to communicate across inevitable language barriers. Struggling enclaves will have to join hardier ones for individual survival of the individual, let alone societal.

  • $\begingroup$ So that means I can’t actually write my story then, can I? $\endgroup$
    – DT Cooper
    Commented Jul 1, 2020 at 18:40
  • $\begingroup$ The minimum viable population applies over many generations, which your story doesn't necessarily need to focus on. Tweak the fertility rates, increase the number of survivors (though they don't necessarily need to know that), allow a modicum of technology, introduce some handwavium miracle cure; there are a lot of easy fixes, some of them pretty minor. IMO the simplest is "a group of ~1-10k survived in relatively good health, but has remained hidden", which allows you to write the story however you like $\endgroup$ Commented Jul 1, 2020 at 18:57
  • $\begingroup$ @DTCooper - what Punintended said. Just have more survivors! Depending on the size of the nuclear exchange, it just might be major cities that got annihilated. $\endgroup$
    – jdunlop
    Commented Jul 1, 2020 at 19:44

Radiation affects fertility in men much more than fertility in women. Like @Willk pointed out, eventually there might only be a few fertile men in high demand.

I'll focus on the second part of your question: What can be done?


The survivors should immediately try to migrate to a minimally radioactive location, if it exists. If it is very far and they have no means of transportation, they will be walking for months like the American pioneers did.

Avoid the rain

At all costs, stay out of the rain, especially immediately after the detonations. Radioactive particles get swept up into clouds, then rain down in concentrated form, called "rainout". Never drink from rivers or any other natural water source, especially after a rainstorm. Hopefully, they have brought their own water supply with them. If not, getting hydration from eating plants might be the next-best strategy.


A lot of radiation comes from radioactive particles stuck to your skin.

The U.S. Department of Health and Human Services Radiation Emergency Medical Management created a document for Procedures for Radiation Decontamination. Take a look, but the short version is:

  • Always immediately extract all metal from any open wounds.
  • Immediately irrigate open wounds with uncontaminated water.
  • Dress any open wound immediately.
  • Wash your whole body with soap as frequently as possible. Use a sponge if uncontaminated water is scarce. If there is no uncontaminated water, brush down all skin with a dry brush or rag.
  • Flush out your ears with uncontaminated water regularly.
  • Brush your teeth, rinse your mouth, and gargle with uncontaminated hydrogen peroxide frequently.
  • Irrigate your eyes with uncontaminated saline water frequently.
  • If possible, measure your radiation after performing hygienic tasks to determine if you are at no more than 2 times background radiation level. If not, repeat these steps if possible.


Radiation takes time to damage male reproductive organs, so hopefully by following these steps, your survivors will be able to mitigate the harm.


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