There is some data that suggests that the types of radiation present in cell phones has caused defects in unborn chicken embryos. The amounts of radiation in these studies tend to be exponentially larger than the radiation put off by a typical cell phone, however. Other research has shown a link between cell phone radiation and cancer in mice. Again, these studies are inconclusive. More recent studies have also shown that there may be a correlation between cell phone usage and hyperactivity and issues in the ability of the child to concentrate as they get older, though researchers don’t all agree on these findings.
Currently in the US cell phones and even cell towers have to meet federal guidelines with regard to the magnitude and frequency of their emission. The CDC has found no link between cell phone use and any difficulty during pregnancy. As a new technology, there are few long-term studies that can support or deny any claimed risk. The research is ongoing in this field and the studies vary in what they discover. To be on the safe side, a pregnant woman may want to limit cell phone usage while pregnant.
As with any other product, you should try to be aware of manufacturing defects and recalls. There have been cases where cell phone batteries have combusted during normal use. Such an occurrence is, obviously, not likely to be healthy for you or for your unborn baby.
Your best bet would be to discuss your concerns about cell phone usage with your doctor. He or She will be able to give you information on the most current research conclusions.