I have never herd of anything like this, and honestly find it very unlikely. At brothels we go through many safety precautions to ensure that this doesn’t happen. We don’t have sex without protection, and if a condom does brake (which is rare) then we have many options. Most girls are on birth control or we have access to several forms of contraception.
I have seen girls working and getting pregnant by clients in the illegal world, but we hold ourselves to a higher standard. You also have to think that if we are having sex with clients without protection, it’s not going to be too long before we catch something and girls like that don’t last too long at a place like Sheri’s, where we are tested regularly.
As a father I can tell you you are not going to hurt the baby. Sure later on in the pregnancy you may not be able to do some positions but there is nothing like having them on top or doggie style with that pregnant glow and getting off at the same time. Just my personal opinion. I think there are few things sexier then a happy woman late in pregnancy.