If sex when you are so far along is relly uncomfortable girls, try spooning for sex, that way your belly can rest on a pillow, and hubby can be really gentle.
I am not sure as what things work,,,but i will give you a list of my failed attempts after being given them from advising friends:
DO NOTS!!
Curries - they just give you heartburn
Rasberry leaf tea- it just tones your uterus
Cod liver oil - gave me the WORST diarroeah in my life,,,honestly the worst one of all!!
horror movies - just gave me nightmares
resting bump against washing machine on spin - my god, how stupid can the suggestions get?? didnt even try this one in case it was actually dangerous for bub
Mowing the lawn - They can blow this one out their ass,,,,,,what 40 week pregnant woman wants to go mow the damn lawn??
Driving over bumpy roads - gave me a bruised feeling belly

I am sure the list goes on, but they were all the really bad ones my family tried to insist we try,,,,,ended up having a c-section anyway