I heard that acrylic can cause birth defects, I would speak to your doctor about it before having them done. My doctor advised me to stop having my nails done. My doctor also advised me against having my hair colored but I still had my hair done. I never had my nails done because of fear. Often the nail tech will tell you the nails are gel but they aren't, they're acrylic.
I was reading in a pregnancy magazine the other day that's it perfectly ok to get your nails done so long as you have them done in a well ventilated place and they suggested you bring your own, clean, manicure instruments to avoid infection from improperly cleaned tools.
Just wear one of those masks like some of the nail artists wear. You can get them at any hardware store or if yours does wear them ask if you could have one. Just to be on the safe side. Heck, they wear them so there must be something to it. Well some do...Ofcourse they are in building all day.
i know that pedicures are bad while pregnant due to pressure points in your feet, i wouldn't think that actually getting your nails done would be bad but I am almost sure the fumes that are in many nail salons could harm your pregnancy