Leaven is used in a good sense in The Parable of the Leaven . As the leaven is in the dough and affects it, the Gospel in an honest heart affects it. The leaven in this parable pertains to the growth and expansion of the kingdom in the sin-blackened world. How we influence the world depends on how much of a godly affect the Gospel has on us. The significant factor regarding a Word-filled kingdom and the primary way it resembles the affect of leaven in dough is that it multiples itself.
Commentators differ regarding whether the woman and the three measures of meal have significance.
Other than that, the meal is a detail of no major importance. Likewise, the woman is largely incidental to the teaching of the parable. The domestic circumstance of a woman baking bread is merely part of the vehicle by which Jesus taught a spiritual lesson. Bread was a staple in the Jewish diet. Therefore, its production was a familiar routine in their lives.