Some studies have suggested that a high body temperature in the mother can possibly be associated with certain birth defects, specifically neural tube defects. The fetal neural tube closes and has developed completely by about 28 days after conception, so this high fever would have to occur very early in pregnancy.
If high fever is caused by an infection or by influenza, these sources and not the fever itself can cause a wide range of birth defects and problems with the unborn baby. As always, it is a good idea to consult with your physician if your temperature reaches 102 degrees.
Fever can safely be lowered in pregnancy through the use of Tylenol or tepid baths.