anybody got rules for the odds of getting pregnant?!

[paulewaug]

OK two of my Player's Characters are getting into a little bit of a trist.

I like the idea that they may have an "oops" child as a result of this but not to the point of using the DMs power to railroad this to happening.I know it seems kinda weird but it is easier than just saying,
"Well look at that, ya'll done went and got pregnant!"
and I don't want to just blow off the odds of it happening just because that would be easier..

I was just wondering if there is a Random way to determine if it happens.
What are the odds of unprotected sex leading to pregnancy?!
It has to better than 1% since that is the margin of error for Protected sex.

 

[hong]

Not that I've gone looking for it, but you'll probably find what you're looking for in the Guide to Unlawful Carnal Knowledge:

http://www.netbook-of-uck.net/

And even if you don't, you'll probably find a lot more things as well....

(Also, try posting in the Unlawful Carnal Knowledge thread that floats around on this forum.)

 

[Plane Sailing]

Given a natural pregnancy rate - that is, the Pearl index without any birth control - estimated as 80, the cheapness of natural family planning, and the acceptability of natural family planning to many cultures and religions; the World Health Organisation undertook an international study.

Source: www.fertilityuk.org/nfps831.html

So you might give as high as 80% of women might get pregnant within a year.

However, for a one-off liason, there is an approx 5 in 30 chance of ovulation occuring within the lifetime of the little wrigglers, and so a 16% chance of conception on this occasion is reasonable.

Cheers

 

[Drawmack]

I would shorten the monthly cycle to 25 days (makes the math easier but it's close enough). Ovulation happens on the 12 and 13th days of the cycle. (yes it's shortened by a day too) Then I would select a random day and start counting her cycle from there. Each day is 4% cumulative until the 14th day when the chances decrease by 4% per day. Just remember that sperm live for three days so each trist forces three checks with increasing/decreasing chance of pregnancy.

 

[Celebrim]

What this ammounts to is that all other things being equal you roll a d6. If it comes up a 1, she's pregnant.

Anything else is probably unnecessary complication.

Celebrim has been in campaigns both were a PC got someone pregnant, and a PC became pregnant.

 

[Dakhran the Dark]

I used to have a mechanic for this in 2nd edition, but it no longer works for 3E...after all, there's no save vs. rods...

 

[Corlon]

I used to have a mechanic for this in 2nd edition, but it no longer works for 3E...after all, there's no save vs. rods...

hey, no puns like that allowed!

Who cares, just say they're pregnant, or make up a percentage, it doesn't have to be realistic

 

[der_kluge]

Hong is right; the netbook of unlawful carnal knowledge has such tables. They should still be applicable to 3e. IIRC, they had percentage chances based on different racial pairings. Like, if a halfing and a human had sex, or two elves, or a human and an elf, etc, etc. Maybe not that extensive, but some pairs were there.

In a real world sense, there's only about a 2-day period where a female can actually become pregnant, and then you also need to factor in age. If the female is older than about 25, her chance drops sharply, it drops even further if she's older than 35.

So, to be realistic about it, you'd need to know when her menstrual cycle is, and for that you'd have to have a calendar revolving in your world. Typical ovulation occurs about 2 weeks after her menstrual cycle.

Or, just to be easy about it, you could roll 3d10. To determine the day of the month. Roll another 3d10 to determine what day her menstrual cycle starts on. If the day of the month is equal to the day of her menstrual cycle +14, then I'd go with something like the following:

Female's
Age:
< 25 --- 90%
25-30 --80%
> 30 --- 60%


I can't believe I just posted all this.

 

[Tonguez]

What this ammounts to is that all other things being equal you roll a d6. If it comes up a 1, she's pregnant.

Anything else is probably unnecessary complication.

Celebrim has been in campaigns both were a PC got someone pregnant, and a PC became pregnant.

I agree with Celebrim here (ie stuff the mathematics!) but if you want a rationale

the 'window of opportunity' for sperm to fertilise an ovum is say 1 week in 4 (a month ie 1d4 1 = pregnant) however this varies across the week hence 1d6 (to account for this variation)

the other method I'd use is a d2 - heads shes pregnant, tails shes not

 

[Tewligan]

I wouldn't spring pregnancy on your players unless you've talked about it with them and they're cool with the possibility. Yeah, people get knocked up in real life, and it forces some big lifestyle changes. If you and your players have no problem with the PC's adventuring life becoming a lot more difficult or being put on hold, then go ahead - it could make for some interesting RPing. However, PC's are usually bigger than life. They fight, live, and love with gusto. I'd be hesitant to punish that with something as impacting as pregnancy just because it might happen in the real world.