generally when you first get pregnant you're put through a good round of blood work which should discover if there's an STI present. Discuss it with your doctor, but often during pregnancy your body doesn't self lubricate like it used to and sex can cause iritation. It's actually a good thing to pee after intercourse but it can burn a little.
Maybe it is just cystitis and when you have sex it's aggravating it . Go to doctors im sure it's just a little infection
Sometimes it can just be from lack of lubrication. That is what had happened to me and so doctor said to use a natural lubricant. they can give you some suggestions of safe ones to use
I have had this too. Turned out it wad chlamydia, was terrible finding out and explaining to my bf, whom it did not come from, but have had it since before him. Check it out, get a pap done. It's treatable during pregnancy. Also can cause some spotting. Most cases it goes without any symptoms, but ask your man it it burns when he pees also. And if you have a lot of white or pink discharge... Hope that helps. I was told its rather common nowadays.
Have you asked your doctor about it? Let me know please
Im also having the same thing im 7 weeks pregnant