Realistic childbirth mod adds countless valueble features! Including 3 types of home-birth, c sections, natural hospital birth, expanted breastfeeding, etc.

Your sims can have a water birth, give birth on their bed with a partner helping, and give unassisted home birth. This mod has added countless features, and Pandasama is constantly adding more!

Heres the link: https://www.pandasama.com/product/child-birth-mod/ 

Adds sooooooo many features, most notibly (for this challenge at least) variable fertility! Every sim has a different fertility level that changes over time, and some are born infertile! It also adds variable miscarriage rates that change from sim to sim, AND depend on the health of that sim! 

Heres the link: https://www.patreon.com/posts/75983577 

Sickness! Sickness! Sickness!
This mod adds all sorts of illnesses, be they allergies, pregnancy complications, diabetes, or appendicitis.
And yes your sims can go to the doctor! They did have doctors, and with this mod, all that happens is it tells you what your sim has, doesnt force them to take medicine!

Heres the link: https://www.patreon.com/posts/health-related-84780509  (be sure to read the description closely)