Sex puts more air in there than oral sex ever could IMO. Granted, everyone's technique is different, butunless he's intentionally blowing air straight into your vagina, I think you will be okay. The baby is very well protected.
That would hurt baby though... Might just make you queef. Sex can put air in there too.
With all my pregnancies I have been told its not safe because some men blow air. Causing an air bubble.
Nothing that goes near your vag can get to baby... Baby is protected by the fluid filled membranes, your cervix, and mucous plug. If it was dangerous so would be swimming, bathing, sex, and gym exams. Oral sex is fine while pregnant, my husband loves it and hasn't complained about any weird taste or smell but everyone's hormones do different things.
Women are not suppose to have oral when pregnant because you can get air up there and cause damage. Also remember while pregnant we release a lot of hormones. Im sure your ok.
I would talk to ur doc.... I don't allow my husband down there while I'm pregnant cause last pregnancy he said it tasted weird so I was embarrassed and this time I've kept him away completely! Good luck and no question is to crazy for ur doc ;)