Should we have sex or better not to ?

Hey girls!

So I’ve a question and I’m hoping maybe one of you have experienced similar and have an answer for me.

So since I’ve found out I’m pregnant at 4 weeks I’ve been experiencing brown discharge everyone 3-4 weeks. I’m now 21 weeks and all is going well, I had been told that my placenta was a little low but I had my anatomy scan yesterday and that has all moved up now. But because of the brown discharge I have been afraid to have sex since being pregnant. Is it best to not have sex when your experience brown discharge? I’m just so afraid that if we have sex it will cause a proper bleed or something. Any thoughts ?