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The Multiple Birth Adjuster (MBA)

by Ashleigh825 Posted 15th Jun 2010 at 11:08 PM - Updated 15th Sep 2011 at 8:17 PM by Ashleigh825
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What Does This Mod Do?

This mod adjusts the chances of having a multiple birth up or down depending on which .package file you download.

There is the original file, which contains chances that are a nice balance between in-game fun and hardcore realism. Additionally, there are files that eliminate multiple births altogether or increase them to roughly 50/50 or skyrocket them to ridiculously high chances.

Please look at the Flavour Packs section to see which file does what.

What are the EA Defaults?

Without a mod, Fertility Treatment or other in-game method of altering the chances of a multiple birth, these are the odds of conceiving multiple children:

Twins: 2%
Triplets: 0%

(These figures are rounded, meaning that triplets have less than a 1% chance of being born, but can still be born without Fertility Treatment).

Although technically extremely realistic, I found that my Sims almost never had twins, let alone triplets. I always had to use some sort of in-game fertility booster and then it was almost certain that there would be more than one child born. I found this boring and not at all fun, so I changed these odds to be just high enough that twins could be born semi-regularly without being common births and triplets were much rarer, but were still born on occasion. As stated above, I aimed for a nice balance between in-game fun and hardcore realism.

I AM AWARE that you can easily use in-game methods of having twins or triplets; however, these methods almost guarantee a multiple birth and leave virtually no element of surprise. They also only affect your active Sim, not the neighbourhood at large. This mod is a global mod, which means that it will affect ALL households in the neighbourhood, whether you are actively playing them or not. It also leaves the business of twins and triplets highly up to pure chance, making it a nice little surprise when you do conceive twins or triplets.

Please do not ask me to create a mod that affects only the active household, as you don't really need a mod to have a multiple birth in your active household. You can easily use in-game methods for that and therefore, a mod that does that would be utterly pointless.

Any comments pointing out that this mod isn't "realistic," that you don't need a mod to have a multiple birth in your active household, or requests to make other versions of this mod will be ignored, as these issues have all been clearly addressed and explained here, already. It will be assumed that you didn't read this. As far as I know and have received word of from testers, this mod does exactly what it was designed to do; no more, no less. Comments saying that you dislike this mod because you don't like what it does will also be ignored as they are irrelevent. Only comments that report actual bugs, glitches or conflicts with this mod will be addressed.

Flavour Packs

Ashleigh_TwinsTripsChance - This is the original file I created to create more balanced odds of conceiving more than one child at a time. This package will give your Sims a 10% chance of having twins (same as in TS2) and a 3% chance of having triplets.

Ashleigh_TwinsTripsChanceNone - This gives your Sims 0% chance of ever having natural twins or triplets. You must use the Fertility Treatment if you want any chance at all of conceiving more than one child at a time.

Ashleigh_TwinsTripsChance50-50 - This gives your Sims a 50% chance of conceiving twins and a 10% chance of conceiving triplets. Much higher than the realistic base package.

Ashleigh_TwinsTripsChanceTonnes - This is for people who LOVE multiple births and want tonnes of babies in their game. This gives your Sims a 90% chance of having twins and 50% chance of having triplets. Obviously, this means your Sims will likely never have a single birth. Not recommended for people with slow computers as this flavour pack can easily overpopulate a town, causing decreased game performance.

Feel free to adjust these values up or down even further as you please if you are familiar with XML Tuning. Just open up the .package file in S3PE and adjust the values to whatever your heart desires.


This mod should be compatible with all patches and expansions. Unless a patch or expansion comes out that alters the multiple birth values in the Pregnancy XML file, I don't see any reason why this mod would conflict. Still not sure? Try it yourself, then let me know if there's a problem. I'm sorry for the rudeness, but I'm getting tired of being asked if this mod is still compatible every time a new patch or expansion is released. Any comments asking if this mod is compatible with X patch or Y expansion will be ignored because it will be assumed that you didn't read this.

This mod WILL conflict with any mod that alters the Pregnancy XML file. In other words, any mods that change pregnancy length, alter water breakage, alter days off work for maternity leave or in any way change how pregnancy works. All of these are in the Pregnancy XML file.

This mod IS compatible with the EGC, all sliders and slider hacks, Twallan's Story Progression, Twallan's SuperComputer and Twallan's Careers mod.

These flavour packs are NOT compatible with each other! They all alter the same values in the same file and will therefore conflict and cause game problems. Only choose ONE of these packages to install.

Thank Yous

Twallan - His SuperComputer mod allowed me to see the chance of multiple births in my pregnant Sims.

MTS' XML Tuning Modding tutorial for The Sims 3.

Download files

Filename Size Downloads Date
Ashleigh_TwinsTripsChanceTonnes.rar | "MOAR BABEHS" package. 90% twins. 50% triplets.

Size: 3.8 KB · Downloads: 7,643 · 15th Jun 2010
3.8 KB 7,643 15th Jun 2010
Ashleigh_TwinsTripsChanceNone.rar | "Single Birth Only" package. 0% twins. 0% triplets.

Size: 3.8 KB · Downloads: 1,194 · 15th Jun 2010
3.8 KB 1,194 15th Jun 2010
Ashleigh_TwinsTripsChance50-50.rar | "Toss A Coin" package. 50% twins. 10% triplets.

Size: 3.8 KB · Downloads: 6,856 · 15th Jun 2010
3.8 KB 6,856 15th Jun 2010
Ashleigh_TwinsTripsChance.rar | "Realistic" package. 10% twins. 3% triplets.

Size: 3.8 KB · Downloads: 7,896 · 15th Jun 2010
3.8 KB 7,896 15th Jun 2010

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Expansion/Stuff packs required:
Sims 3

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Tags: #twins, #triplets, #tuning, #babies, #XML