Old women's saying about breastfeeding

I love old women's saying and I am curious to hear yours about breastfeeding.

I start. Where I come from, they say a breastfeeding woman should immediately stop breastfeeding if her menstruation starts, because it poisons the breastmilk so it will not nourish the baby. So if there is a very skinny child, they wonder if the mother breastfed during menstruation.