Will 1 glass of wine hurt or help?

I am 24 weeks pregnant and I just woundered doctors say 1 glass of wine with dinner is healthy for you but is it still ok when you are pregnant or should you not have that glass of wine with dinner. Mind you I have not been drinking at all since finding out I am pregnant I am just woundering if it would help or hurt if I were to have that 1 glass with dinner every night.