There are differing opinions on that topic. There are some physicians who advise pregnant woman to get sunlight in their first trimester because sunlight is the body's natural way to manufacture vitamin D. That's healthy for the mother and that's healthy for the baby. Many tanning salons are conscious of the fact that pregnant women should not be exposed to excessive heat. While tanning units are regulated to maintain the temperature below 100 degrees during the short duration of a tanning session, many feel that it's a simply isn't worth the risk for a pregnant woman to tan during her pregnancy and so that is really the origin of the concern about tanning during pregnancy. It has little bit to do with ultraviolet. It has more to do with heat and comfort. It certainly isn't worth the risk to the mother or the fetus to expose them to an excessive heat. There have been studies done at John Hopkins University with jacuzzis and pregnant woman. There were apparently pregnant women who utilize Jacuzzi tubs who had a slightly higher risk of the baby developing spina bifida, a bone disorder. That is the origin of the concern about heat. I personally do not believe that an indoor tanning even that delivers the same type of heat that Jacuzzi would. However, many people just simply do believe that it is a risk not worth taking. So, it's certainly best to be conservative when you're pregnant. However, there are doctors who believe that women in their first trimester should be in the sun. So, it's not necessarily universally condemned.
