Chris Hatch Alternate Pregnancy Controllers will allow teens to "be" pregnant and it will also allow elders to "be" pregnant but you need another mod to "make" them pregnant by, either a mod like the Sim Blender or Chris Hatch Free for all bed.
Alternate Pregnancy Controllers and Free for all bed are both at BAS or Back Alley Sims. Is an adult site and I will not link to it here.
These 4 are the top in there class with InTeen having all the bells and whistles.
My personal favorite at this time is the S2L mod.
InTeen will age up the teen while pregnant to adult in age only while still in teen body, all the other ones leave them as teens in both body and age.