hello there Pica is the term used to describe the intense craving for and eating of non-food items, such as soil, clay, laundry starch,chalk, ice, ashes, plaster, paint chips, and coffee grounds. No one knows what causes these unusual cravings, but a combination of biochemical, psychological, and cultural factors may be at work. Pica has also been linked to iron deficiency anaemia­, even though none of the craved items contain a significant amount of iron. If you crave non-food items, it doesn t necessarily mean you have any sort of deficiency. And it definitely doesn t mean you should consume them. In fact, eating non-food substances can interfere with your body s ability to absorb nutrients and may even cause a deficiency. Eating non-food items may lead to illness, such as lead poisoning or bowel blockage. It also increases your risk of having a preterm birth and, in rare cases, may even cause death. Though nothing is 100%proved, still one thing is sure that these non food items like chalk have no benefits whatsoever. So its better you avoid them. Its good you have reached your term 37weeks and if the baby s growth as per ultrasound is normal then dont worry. But definitely get you blood tested for heamoglobin level to rule out anaemia as if present it may complicate your delivery with excess bleeding. To avoid further eating, wheneva you have craving for chalk eat something like a toffee or chewing gum so that you leve the habit. take care