Dying hair while pregnant

So I have a wedding to go to in July. I will be 6 months pregnant. Is it possible to dye my hair if everything is well ventilated or even if I dye it outside? My last pregnancy I had no gray hairs. But now I got some. I'd be fine if my gray hairs were every where but it just in one selected spot, at my callick. My fiancé is a groomsman in the wedding so I'm sure I would be in plenty of pictures. Sorry for the dumb question just wondering.