Also - http://www.buzzle.com/articles/tanning-while-pregnant.html
Very high temperatures are used during the tanning process. Research suggests that the body temperature of an expectant mother should not rise above 102º Fahrenheit. The high temperatures can cause the body temperature to rise as well, which can be fatal for the fetus. It can lead to increase in body temperature of the baby. Unlike the mother, the baby will not sweat inside the womb, causing immense damage to the baby.
The doctor was again, correct. Although he gave your friend a "dumbed down" version of what was happening to the baby the short of it is she could have killed her baby. Her sunburn was of great concern to the doctor.