Fertility and Protection – a Sims 4 mod

(Relationship & Pregnancy Overhaul mod #2)

Pregnancy Risk, Protection & Fertility – related features

———————– Fertility and Pregnancy Risk———————–
  • lets you choose between either a global rate or an individual rate system!


  • Global rate: can be set in Settings


  • Sims who can impregnate AND sims who can be impregnated have a fertility rate.
  • Fertility is auto-assigned within a range that depends on age, unless you have the extra option file to have it be a default for everyone.
    Auto assignment has 5% chances of making a sim infertile.
  • You can adjust a Sim’s fertility rate at any time.
  • Sims who can be impregnated can have their fertility set to vary cyclically. You can also make it so that they all do by default with an extra option file.
  • If you ever need to re-assign fertility metrics to a Sim (say, if they changed CAS gender options for example), you will be able to do so under ‘family and pregnancy’ then ‘fertility’ then ‘options’.

WooHoo has a chance of causing pregnancy. The chance is a number based on the fertility of each Sim involved and some minor other factors.

Protection (woohoo protection items & birth control) can be used. These methods have a 5% failure rate. If they fail, the risk rate as mentioned above will be applied.

“Try for Pregnancy’ can be done only on beds. It is the same as WooHoo but with a deliberate attempt at getting pregnant. Chances of pregnancy with it are 50% higher than without.

More details on Try for Pregnancy success chance increase: It takes the base chance for the Sims involved, and increases it by 50% of itself; so, it basically multiplies the chance by 1.5. The result still depends on the sims’ individual rates.
For example, if a sim has 12% fertility, their partner has a 3 out of 5, and they try for pregnancy, ignoring other factors here, it would go 12% x 1.5 = 18.
If a Sim has a fertility of 25, their partner has a 4, it would be 25 x 1.5 x 1.3 = 48%. Etc.

Sims who want children will be happy to do it. Sims who don’t will be likely to refuse, and when doing it won’t be too happy about it. You will see it in their acceptance animation and in a moodlet.

Sims who are indifferent or want children get frustrated after several attempts that don’t lead to a positive pregnancy test. Down the road I will make interactions for this to cause conflict in the couple.

Drinking a fertility potion will increase chances.

———————– Protection ———————–

Using them: You don’t need to do anything with them; if your Sim has them, they’ll get used, you’ll get a notification saying “Protection was Used” (unless your Sim is WooHooing with someone they agreed to not use protection with).
If your Sims somehow have no protection and are WooHooing autonomously, or if you made it so that they WooHoo without protection, you will get the following notification, in a different color so that you can intervene and sent them to get an emergency pill if you so wish. 

Checking if a Sim has protection: You can check at any time how many you have in your inventory. Your Sim can ask others if they’re on birth control or have items; if they do, then it doesn’t matter whether your Sim has anything or not (for obvious reasons), they’ll both be protected.

Buying them: WooHoo Protection Items can be bought through a Rabbit Hole, and also ordered through the computer game-style (meaning, available immediately), if for whatever reason you want to skip over the realism of going to fetch them and get them instantly instead. You can place them in world, give them to other Sims, etc etc.

How it works: It protects from pregnancy, but not WTDs (WTDs are an optional feature, read ore about them below). Hormonal birth control is time-based. It automatically renews every 7 sim days. To get off of it, your Sim needs to decide to stop, through an interaction.

How to get it: A Sim needs to book a family planning appointment on the computer. After the appointment, the Sim comes home on birth control.   If your Sim is on birth control, a Sim who wants to have children will have the ability to ask them to stop it. This is for those who play relationships with NPCs, so that you have a way to have the result you want without needing to make the other Sim playable.

Side effects: Yes, hormonal birth control has side effects… Moodlets of 1 to 2 points, mostly 1. From being unable to get flirty for a day to spotting, not forgetting headaches and nausea…

  • Ask to Stop Using Condoms: these Sims won’t use condoms together anymore, but would still with other partners
  • WooHoo Without Protection: to skip condoms just once
———————– Sterilization-related Features ———————–

Sims can go have sterilization surgery and procedures to reverse that. After that, they can tell their partners about it (under “WooHoo Wellness”. Reactions depend on pregnancy wish.

There is also an interaction under “Romance” to announce being infertile to new partners with whom a first kiss has already been exchanged.
Sims can ‘Ask about Fertility’ to others with whom they’ve had a first kiss.

—– Other Useful Interactions —–

Useful Interactions

* Cheat under ‘Reproductive health’ to easily & quickly switch impregnation attributes.

  • More cheats under various menus!
    For an example, the ‘Pregnancy’ cheat menu, located under the main ‘pregnancy’ menu:

When pregnant:

VS when Not Pregnant:

———————– Compatibility, Troubleshooting and FAQ———————–

For latest compatibility info, see the latest download page, linked on the download index post.

Troubleshooting and FAQ

For latest compatibility info, see the latest download page, linked on the download index page

No. WW interactions are their own thing and I’ve no business impacting it. WW interactions recognize my birth control and infertile trait, but that’s the extent of integration on that.
If you want, you can turn off pregnancy risk from WW and “Mark Sims as WooHoo’d With – With Pregnancy Risk” in my mod (under ‘actions’) after Sims do WW stuff. This will apply my system – provided that you set WW to let my mod impact the game stuff (check compatibility info on download page for correct settings).