Studies show about 90 percent of pregnant women have cravings, particularly in the first trimester. Cravings for pickles and ice cream are pretty standard. But some women get strange cravings for stuff like dirt and clay; it's called pica, and luckily, it's pretty rare during pregnancy. We don't know for certain what causes pica, but according to the Journal of the American Dietetic Association, it could be connected to iron deficiency. What's scary is nonfood items may contain toxic ingredients that can potentially harm both you and baby. So if you're experiencing unusual cravings, contact your health provider.