Coffee helps morning sickness???

Vallery
Ok so I'm on my 4th pregnancy (7 weeks) and I was sitting here sipping on my cup of coffee... I know caffeine isn't great but been given the ok for 1 cup by my doctor... well I starting thinking back with my first I had horrible morning sickness but with the others including this one I've had none... I've had all boys I don't know the sex of this one obviously the only difference from my first and the others is I didn't drink coffee with my first... I was just curious if there is a connection between drinking coffee and no morning sickness???