Studies suggest that food cravings change during pregnancy due to hormonal fluctuations. These hormonal changes affect your sense of smell, taste and appetite, making you crave for strange aromas, textures and combinations of foods. 

These cravings often signal what minerals and nutrients your body needs, but tend to come in the form of unhealthy or strange foods. For example, cravings for desserts like ice cream are commonly reported among pregnant women. Ice cream is a good source of calcium (around 60g per half cup), but tofu has around the same calcium content for the same serving size and is a much healthier alternative. A peculiar pregnancy condition called pica, where pregnant women crave strange foods like chalk or clay, is similarly thought to arise from a deficiency of certain nutrients.