"One glass of wine" while preggo

This is just a curiosity post. I have heard many people tell me to "drink one glass of wine" a week to relax. I've even heard doctors give this advice. My sister told me she had one glass a week throughout her pregnancy. I'm 17 weeks and have not had any alcohol since finding out I'm pregnant and I'm not planning on it but I am wondering what other pregnant mommas thoughts are on this topic... PS, no judgment here!