I found a list of things being introduced in Sims 4 and some sound really good
Sims in labor are still playable, so they can still eat and watch telly and talk to people
Pregnancy tests and breastfeeding
Maternity leave isn't mandatory
Pregnant sims can look different according to their body shape, and all clothes are available as maternity wear
You can bake birthday cakes!
You can die of laughter, and you can be scared to death
Parents can have the "woohoo talk" with their kids
Different types of Woohoo (that's such a ridiculous word by the way ) - exciting woohoo, unsatisfying woohoo.
If you don't pay bills your water/electricity get shut off
Violins! (I used to be a violin player so this is exciting for me)
Still, I won't buy it unless I find it for really cheap. I'm still disappointed by everything missing