I advise not to have a tan in the first 3 months. This has nothing to do with it not being safe, it's due to hormonal changes that can make the tan patchy!
Some people would rather not spray clients who are pregnant but i have no problem with it.
Make sure you have your gun turned down low and there is plenty of ventilation.
I actually had a pregnant client pass out on me just last week.
She hadn't eaten that morning and she went to the doctors straight after and was suffering with low blood pressure.
I think this would have happened to anyone with low blood pressure and who had not eaten, so it would not put me off spraying someone who is pregnant but it will make me ask more questions before i start spraying!
I've also had someone throw up as well and they weren't pregnant!
As long as you feel comfortable with it then there is no reason why you can't spray someone who is pregnant.
You can also use sniffits to go in the nose which i think you can get from wow products.