Pahlavi Texts, Part III (SBE24), E.W. West, tr. , at sacred-texts.com
1. The seventeenth subject is this, that when they cut a toothpick (hilâl), or a splinter which they wish to apply to the root of the teeth, it is necessary that they retain no bark. 2. For if a small quantity of bark be on it when they apply it to the teeth, and they cast it away, if a pregnant woman puts her foot upon it, the danger of that may be that the child comes to harm 1.
278:1 Owing to her fear of having stepped on dead matter (see Sls. X, 20, XII, 13).