It's fine.... I got mine done for most of my pregnancies...
I do mine myself, using the gel nail varnish n uv lamp
I've gotten my nails done quite a few times during this pregnancy, almost 38 weeks, and my Dr said to just find a well ventilated place. If I walk in and there's no fans and it smells horribly of chemicals then I walk right out. I've found the places that cost more are better because they're very well ventilated and don't smell of chemicals.
Also recommend that they turn your seat facing away from the person that's doing your nails as well as away from the products.
Are talking about just a common manicure or a full set?? Either way, definitely use a mask! I bring my own, I get a full set monthly and a fill in as need be, between month's. Getting a full set requires more steps and chemicals used are stronger then those of a gel set or a average manicure. My OB recommended I use a mask and wash my hands and face afterwards, which I do.
I went and had mine done if it's too much for you just ask for a mask.