UPDATE!
I changed age mod (thanks to this thread, I finally did..)
No preg mod still, so pregnancy lasts as default lasts.
Babies 5 days,
Toddlers 15 days.

Nope to both questions.

1. Do you use a pregnancy span mod in your game? Yup, just added one a couple months ago.
2. If you do, how long are your pregnancies? 48 hours
3. Do you use an age mod? Yes, a self-tweaked variant on TwoJeffs' Age Duration mod
4. If you do, how long are the baby and toddler stages? Babies = 2 days, Toddlers = 3 days

I do not have mods for pregnancy length nor for baby/toddler lengths.

only time length I have modded so far is semester lengths; my own creation.
when I get Seasons, I would attempt to mod season length.

1. Do you use a pregnancy span mod in your game? No
2. If you do, how long are your pregnancies? The regular amount. I sometimes use SimBlender to accelerate the pregnancy if its starting to get on my nerves
3. Do you use an age mod? No
4. If you do, how long are the baby and toddler stages? The babies are the regular 3 days, and I tend to grow toddlers up 1 day early so usually 3 days for them also (I hate toddlers so I tend to grow them up early when they have all their skills.)

@Orilon since you don't particularly like toddlers, are you aware of this ?
Go ahead, and age your brats right away! No time for skill learning.

1. Do you use a pregnancy span mod in your game?
No
2. If you do, how long are your pregnancies?
N/A
3. Do you use an age mod?
Yes
4. If you do, how long are the baby and toddler stages?
Same as game default.

1. Do you use a pregnancy span mod in your game?
No

2. If you do, how long are your pregnancies?
N/A

3. Do you use an age mod?
No

4. If you do, how long are the baby and toddler stages?
N/A

1. No (unless inteen counts?).
2. Sometimes speed up the pregnancy with inteen.
3. Witches live 7x longer than regular sims, custom plantsim lifespan.
4. Plantsim toddler stage is 10 days long.

1. No.
2. N/A
3. Yes.
4. Baby: 3 days, toddler: 5 days.

1. No pregnancy mod.
2. n/a
3. Yes.
4. Babies are unchanged, toddies are 6 days.

I'm excited to see what you're working on!