Oral sex is generally low risk for STI's - not completely risk free, but low enough that you really need to worry. The STI you'd be most at risk for is gonorrhea or NGU, but you don't seem to be showing any symptoms. Since you have a pregnant wife, I don't want to advise you not to get tested or not to tell her, but, from a risk perspective, the odds of you being infected with anything are actually quite low.
Syphilis and herpes can be contracted even when using a condom as the genital area outside the condom would be exposed when rubbing up against hers. Thats the risk and even if its low risk its too big of a risk for you pregnant wige.
Hi recieving unprotected oral sex is a risk for herpes, syphiils and gonoreha. test for these before being intimate with your wife at the correct window period. Gono--7 days, syphilis--- 6 weeks and herpes at t 3 months. while your at the doctors office tell the doctor about your affairs and concerns for your wifes safty.
Another point to address here, I knew that oral sex can lead to some sort on incurable and asymptomatic throat bacterial disease...
3- how can I know if I caught any??
4- can this be caught by the receiving partner??
5- can it be passed to my wife if she gave me oral sex??