Flash is a high temp for a short period of time. Gentle, I believe is a lower temp and a longer period of time. Both should kill any harmful bacteria. Flash is much more common. Eggs, however, have to be done gently to avoid cooking the egg. I love my gently pasteurized eggs so I can still eat cookie dough!
Re: Pasteurization
Both should be fine for pregnancy.
BFP #2 09/03/17 | EDD 05/17/2018