Suppose two characters have sex in-game. What are the rules for determining if a character is pregnant, how many kids there are (single birth, twins, triples, etc), and the gender(s) of the child(ren)?


3 Answers 3


There are no mechanics in the core rulebooks regarding sex or pregnancy. This is something that would be entirely homebrew, or an RP mechanic between you and whatever you DM decides is appropriate.

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    \$\begingroup\$ Or how to generate descendants, for that matter. \$\endgroup\$
    – nijineko
    Commented Oct 17, 2017 at 21:31

You are looking for the Book of Erotic Fantasy.

Yes, many will tell you that D&D and sex should not mix, they are right. But we don't always do what's right, right? More often than not, someone will see another playing asking the GM "Are there whores in town?", leading to some quick randomization of fun events that will make (nearly) everybody at the table laugh.

While the topic certainly deserves some degree of caution, actually integrating it into a role-playing game is difficult to implement and tends to end badly if you are not prepared and open-minded about it.

Well, that 3rd party book has several sexual related rules for your games. You don't have to use all of them, or any of them. But some are interesting to read (or it was, back in early 2000s). It has several random tables to figure out things like the size of things, gender of things and how certain races will breed with others. It also has several topics that are interesting, like how to integrate sex into your games without it turning into a joke, how certain topics should be discussed with your players, and overall, it offers a mature view on the subject.

Just for the record, the book is not the worst rules splatbook released for 3.5 (and there are many in that category), and the flavor can certainly be adjusted to your tastes. Before the game was even released, it had drawn so much criticism due to the topics being discussed that Wizards revoked their d20 license and they had to publish it under the Open Gaming License instead.

Regardless of that, the book did open up a door for people to discuss sex in d&d, something normally and often frowned upon, like the excellent articles about Pregnancy and Consent from Kismet's Guide to Sex and Romance in Fantasy Gaming.

You will also find homebrew rules for pregnancy on dnd wiki, but those are nowhere near as interesting.

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    \$\begingroup\$ The weird semi-moralizing in the beginning of this answer is really off-putting. Also, while it’s certainly true that Book of Erotic Fantasy has at least some useful material in it, and it’s definitely not the worst supplement for 3.5e, this answer I think goes much too far in describing the book as a whole as useful. Much of it is immature and disappointing, and the mechanical content is wildly imbalanced. \$\endgroup\$
    – KRyan
    Commented Jul 21, 2018 at 18:35
  • \$\begingroup\$ @KRyan we will have to agree to disagree there. Maybe the book is not useful for the standard d&d game, but to the question at hand (How to determine pregnancy) it has enough rules to satisfy whoever is looking for those. I don't remember all the contents of the book by memory, and even if it sounds immature to one person, it may be useful to another that is looking exactly for that level of maturity on their game (even if by a joke). \$\endgroup\$
    – ShadowKras
    Commented Jul 22, 2018 at 17:47
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    \$\begingroup\$ You don’t solely claim it’s useful for the purpose of answering the question, though. The sections on pregnancy are fairly useful. Other sections, far less so—the prestige classes, for example, since they’re liable to break your game. If you restricted your claim to merely answering this question, I’d have no objection to it. Though I would still object to the weird “this is bad, but we can be bad” introduction: it’s not bad if the table’s on board with it, which either makes it weirdly judgmental, or just self-contradictory. \$\endgroup\$
    – KRyan
    Commented Jul 22, 2018 at 17:51
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    \$\begingroup\$ I think this answer would be improved if it actually told us us the rules for determining pregnancy. I understand that "the rules are in this book which has been out of print for years" is sort of an answer, but actually giving us the rules would be better. \$\endgroup\$
    – Dan B
    Commented Jul 23, 2018 at 14:07
  • \$\begingroup\$ @DanB Id have to resort to piracy for that, as I no longer own that book, which I would rather not. But to anyone who happens to have it, feel free to edit the answer. My objective here was merely to point out the existence of the (third party) book, as opposed to "there are no rules anywhere". \$\endgroup\$
    – ShadowKras
    Commented Jul 23, 2018 at 16:46

When Real Life meets DnD

Science time! (Note: I have encountered this as a DM myself)

So, IRL birth is a lot about law of probabilities. You have the female. Her egg will be in different positions (or not present at all) at different times of her cycle. Depending on fertility, she may or may not have produced more than one egg. These are both somewhat random factors determined by so many minor bodily functions that, overall, even modern medical professionals see it as at least partly chance.

Now the male. He will be...ahem..."giving" thousands or even millions of sperm cells in one mating. These cells, however, have to travel what, for their size, is a super-marathon. They don't have a guaranteed chance of actually encountering an egg. That's a bit of probability right there.

So, success of the mating in the first place should be a d100 Roll. As a DM, if the creatures are of the same race/breed and quite healthy, I generally say that any roll over 20 is success. If of a different race/breed or of "meh" health but logically still capable of mating I say that any roll over 40 is success. For really odd combos, unhealthy participants, or other factors that would logically affect it I will set it anywhere from 50 to 90. A totally impossible combination should just be forbidden from success. What constitutes each of these tiers is up to you.

Now, back to science.

Eggs produced determine the number of offspring. So this is also a die roll. Unless otherwise stated for this race in the flavor text ("XYZ mothers usually give birth to four offspring" or the like), as you are both characters assume the standard for humans and set the limit at triplets. Roll a d3 to determine the result.

Lastly, gender. This is a fairly simple d2 roll for each of the potential kids (assuming they had any).

The bigger issue

If these two lovebirds (or more illicit situations) are of the same race, you're good.

You don't make it clear, but generally we assume any humanoids with actual living bodies could mate. As a DM, you have to consider what you plan to do if they AREN'T of the same race.

Generally speaking, there are a few results:

1) Dominant bloodline. If really odd races are in play, you can rule that one bloodline is dominant genetically and entirely overrules the other, making the kids the race of that parent.

2) Unearthed Arcana Bloodlines. If one of the races/beings covered by the "Bloodlines" section in UA is in play, you could choose to use a base race and add a bloodline to it.

3) Hybrids. There are some hybrids listed in DnD -- Half-orc, Half-elf, etc. For races that don't have a hybrid, there is always the option of homebrewing one yourself from the two races involved (or creating something new from the combination, perhaps).

The Pregnancy Itself

Don't forget kids aren't born instantly. Make sure you account for the pregnancy of the mother. Usually 9 months long and progressing as it goes, this carries health factors, limitations, and dangers with it.

The mother, for example, should at some point experience random bouts of the nauseated state. Base land-speed should drop some, as well as carrying capacity. Certain types of damage (or over-exertion) should also come into play as potentially harming or killing the fetuses, resulting in a miscarriage.

Even the act of giving birth is something that should be handled carefully. Births are not always successes and often killed the mother and/or babies involved. That's something that you would need to address as a DM personally, however, because the medical/healing abilities available would determine the risk.

My own experiences here as a DM

I, in general, try to have my players at least avoid this. I would suggest explaining the potential impacts on them in game first so they realized the difference it makes.

That said, if you/they decide to go ahead, I've found it works well. I used in one aristocracy/feudal campaign for players that had family bloodlines and whatnot. The nice thing is that the pregnancy itself serves as a deterrent for future acts of the same kind. Creating new characters has a major plot impact, and is something you should seriously consider.

Out of humor I do tend to use this with Don Juan bard players...and usually results in a good bit of fun by the end of longer campaigns.

Generally, avoid true hybrids. These are drastically unpredictable when the events happen, and can result in totally broken offspring. I use the hybrid effect for rather simple beings usually, or ones that are very close together.

Also, don't be afraid to use DM Omnipotent miscarriages. More than once I have ensured an NPC did not give birth successfully because I knew it would negatively affect the plot.

Lastly, consider the impact of family. This can have cultural, social, and financial impacts on a character, and unless your campaign and players are ready to handle this I suggest against pregnancy entirely. Just DM rule that they are unsuccessful.

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    \$\begingroup\$ ...roll a d3? Triplets as likely as singleton babies? Why not use another percentage roll, and use actual data on human rates of multiple pregnancies? (Though to my understanding, various hormonal therapies available today can increase the chance of having more children, so modern data may be skewed somewhat upward.) \$\endgroup\$
    – KRyan
    Commented Oct 26, 2017 at 14:39
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    \$\begingroup\$ The line that “generally we assume any humanoids with actual living bodies could mate” is actually incorrect, if we’re going by what D&D has generally done. In fact, earlier editions explicitly stated that hybrids were rare and almost all were half-human. We have gained greater variety of hybrids, but even to this day there are no official hybrid races for most of the core races (there are half-elf and half-orc, and Dark Sun has a half-dwarf in the mul, but those are literally the only hybrid combinations for core races). That is not a fair assumption to make. \$\endgroup\$
    – KRyan
    Commented Oct 26, 2017 at 14:45
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    \$\begingroup\$ Oh, and also, you have a typo (I assume) in the first line of the last section: “Don't forget kids are born instantly.” I assume you meant aren't there. \$\endgroup\$
    – KRyan
    Commented Oct 26, 2017 at 14:46
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    \$\begingroup\$ Hi Alphaeus; please check our guidelines for homebrew answers. We request homebrew have a well-founded reason for being presented -- consider that a question asking for the rules for pregnancy is not answered by homebrew, unless that same answer demonstrates there are no rules already. We also want homebrew to be tested out in practice -- we can all just come up with something from our seats, but how well it works out in practice is the real differentiator. Can you include description of how this has worked out for you in actual play? \$\endgroup\$ Commented Oct 26, 2017 at 15:11
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    \$\begingroup\$ @KRyan With non-standard races, anything is possible, hence the d3 roll. As to the mating, I did not say with success. You can mate but not produce offspring, and I did state in my answer that the likelihood of success considered this factor. Fixed the typo, thanks for pointing it out, lol. \$\endgroup\$
    – Alphaeus
    Commented Oct 26, 2017 at 15:27

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