Is it dangerous for a woman to receive oral sex during pregnancy?
I know that you've probably heard something along these lines, I myself heard about this case while in medical school: There was this one case in which oral sex caused an air embolism in a pregnant woman and killed her! Apparently, the male partner blew forcibly into the vagina of the woman. As far as oral sex and homicide, I've never seen it in my experience and I've never actually seen the report on which this "case" was based.
Theoretically, I suppose its possible for oral sex to pose some risk. Since pregnancy is a vascular state, there are large openings to the uterine veins called sinuses which can bleed a great volume in hemorrhagic situations. For the same reason, I suppose they can receive a large volume of anything delivered to them, like air. We see this in a particularly deadly condition called amniotic fluid embolism, in which a sudden bolus of amniotic fluid can enter the maternal circulation. But again, let me say, in my experience I've NEVER seen this happen and I've NEVER read any case about this actually occurring.
I know there are probably some pregnancy books out there that talk about the dangers of oral sex. But let me point out, does anyone really force air in this way during oral sex? Such an act isn't what most people think of as oral sex.
Now since you know the method of danger, you'll know immediately whether your own methods are a danger to you. Probably not.
But if you're still concerned, talk to your health care provider. With high-risk pregnancies, your health care provider might recommend you limit certain practices in the bedroom, like intercourse, just to be careful.